2. Definitions and Concepts
To clarify the structure of the proposed framework, before the definitions and concepts, the overall workflow of the study is divided into three distinct layers, as shown in
Figure 1.
Figure 1. Schematic diagram of the geometric-physical coordinate frame.
2.1. Definitions
2.1.1. Phenomenon (P)
Within this framework, a phenomenon (P) is introduced as a symbolic surrogate and a dynamic unit—a modeling variable rather than a fundamental physical entity—that carries an extensive quantity. This quantity may change and redistribute in space, time, and structure, yet its total amount is always governed by a conservation law, such as mass, energy, momentum, or other extensive quantities that play a fundamental role in nonequilibrium thermodynamic equations. This description aligns with contemporary approaches in the physics of open systems, which emphasize the behavior of flows and exchanges of extensive quantities
| [8] | H. C. Öttinger, Nonequilibrium thermodynamics for open systems: GENERIC framework, Phys. Rev. E, 73(2006) 036126. https://doi.org/10.1103/PhysRevE.73.036126 |
| [11] | D. Jou, J. Casas?Vázquez, G. Lebon, Extended irreversible thermodynamics, Rep. Prog. Phys., 51(1988) 1105-1179.
https://doi.org/10.1088/0034-4885/51/8/002 |
| [12] | D. Zhang, Q. Ouyang, Nonequilibrium thermodynamics in biochemical systems and its application, Entropy, 23(2021) 271. https://doi.org/10.3390/e23030271 |
[8, 11, 12]
.
Each phenomenon is defined not only at an instantaneous moment but along its entire evolution path, extending across the four-dimensional manifold (x,y,z,t) and along the geometric–structural axis L. This description is consistent with contemporary approaches in open system physics, which emphasize the behavior of flows and the exchange of extensive quantities. In this context, nonequilibrium thermodynamic theories and open system frameworks have found a prominent role
| [8] | H. C. Öttinger, Nonequilibrium thermodynamics for open systems: GENERIC framework, Phys. Rev. E, 73(2006) 036126. https://doi.org/10.1103/PhysRevE.73.036126 |
| [11] | D. Jou, J. Casas?Vázquez, G. Lebon, Extended irreversible thermodynamics, Rep. Prog. Phys., 51(1988) 1105-1179.
https://doi.org/10.1088/0034-4885/51/8/002 |
| [21] | Shamohammadi, M. R. Yabaluei Khamesluei, B. Shamohammadi, The Law of Survival of Phenomena and Its Application in the Analysis of Dynamic Processes (2026).
https://doi.org/10.1007/s13201-025-02711-y |
[8, 11, 21]
.
While traditional frameworks primarily focus on “instantaneous” states, contemporary studies indicate that to accurately describe systems, processes must be treated as continuous evolution paths in time and phase space, especially under conditions where entropy and irreversibility play decisive roles
| [9] | Y. Zhu, L. Hong, Z. Yang, W. Yong, Conservation-dissipation formalism of irreversible thermodynamics, J. Non?Equilib. Thermodyn., 40(2015) 67-74.
https://doi.org/10.1515/jnet-2014-0037 |
| [10] | M. Esposito, Open questions on nonequilibrium thermodynamics of chemical reaction networks, Commun. Chem., 3(2020) 107. https://doi.org/10.1038/s42004-020-00344-7 |
| [11] | D. Jou, J. Casas?Vázquez, G. Lebon, Extended irreversible thermodynamics, Rep. Prog. Phys., 51(1988) 1105-1179.
https://doi.org/10.1088/0034-4885/51/8/002 |
[9-11]
.
Within this framework, the components of a phenomenon are defined as follows:
1) pin: input phenomenon entering the system.
2) pT: initial uptake; the portion of the phenomenon that enters the system irreversibly and unidirectionally.
3) pe: equilibrium or secondary uptake; the portion of the phenomenon that occurs after reaching the equilibrium threshold and is associated with reversible behavior.
4) pr: residual phenomenon; the portion of the output that simultaneously appears with pe.
5) pout: output phenomenon from the system, including pout =pT+pe+pr.
6) p: system uptake or product, defined as p=pT+pe.
7) pe,max: equilibrium uptake capacity.
8) pmax: total uptake capacity, defined as pmax + pe,max + pT
2.1.2. Time
In this model, time is treated as a measurable geometric dimension represented by the axis t. In regions of uniform flow, the reparameterization τ=v
pt is employed, functioning analogously to ctctct in special relativity, thereby scaling time consistently with spatial dimensions
.
The equilibrium threshold time T is defined as the maximum time during which the initial uptake occurs. In other words, the irreversible process takes place over the interval .
2.1.3. Phenomenon Input Velocity (vp)
The phenomenon input velocity vp is a measure representing the change of the phenomenon along the L axis relative to time. In the proposed model, this velocity is assumed constant along the flow path of the phenomenon; that is: dL/dt=vpconst.
The constancy of v
p ensures that the input–output ratio along L remains unchanged and that the flux of extensive quantities is modeled uniformly
. Given a uniform input flow, the input phenomenon over a time interval ttt is expressed as: p
in=v
pt.
Examples: Steady gas flow at the input of an ammonia plant, uniform irrigation in a farm, fixed-dose drug administration, batch experiments, and uniform vehicle motion represent cases of constant vp.
2.1.4. Input–Output Mapping
This mapping defines the functional relationship between the input variations of a phenomenon and the resulting output.Within the L framework, this mapping is defined such that its variation along L is zero: ∂(pout/pin)/∂L=0
Hence, the input–output ratio remains constant along L
. This constraint cannot merely be applied as an external constraint to a Cartesian coordinate system because, in that case, the conservation law would only be enforced a posteriori after solving the equations. In the present framework, this ratio is inherently incorporated into the coordinate geometry at the state-space level.
Phenomenal Flux
The phenomenal flux represents the movement or transfer of extensive quantities (mass, energy, momentum, etc.) within the spacetime manifold and along L.
This flux comprises reversible, irreversible, and cumulative transfers and is defined based on v
p and the input–output mapping
. The L axis represents system equilibrium and conservation laws
and satisfies the relation ∂(Flux)/∂L=0.
2.1.5. L Constraint
The L axis is not an independent physical dimension but a geometric constraint applied to the base manifold. This constraint indicates that variations of the phenomenal flux along L are zero:
The L-axis represents the geometric application of the conservation laws
. It is important to emphasize that the equilibrium axis L is not a direct empirical quantity, but rather a geometric construct obtained from the analysis of the system's trajectory in coordinate space and its asymptotic behavior.
Time Reparameterization τ
In regions of uniform flow, the parameter τ=v
pt is used for a more geometric representation of the process. This parameter allows coordinated and mappable changes along both time and L
| [15] | S. M. Endres, Entropy production selects nonequilibrium states in multistable systems, Sci. Rep., 7(2017) 14437.
https://doi.org/10.1038/s41598-017-14485-8 |
| [16] | Shamohammadi, Z., Bustanian, M., Tavakol, H., Removing Cd (II) from water and wastewater by blowy sand; the effects of total hardness and pH, J. Desalination Water Treat., 51 (2013) 16-18. https://doi.org/10.1080/19443994.2012.749365 |
| [17] | Shamohammadi et al. (2023a), Presentation of a rainfall runoff retention model (3RM) based on antecedent effective retention, CivilEng, 4(3) (2023) 966-981.
https://doi.org/10.3390/civileng4030052 |
[15-17]
.
2.1.6. Phenomenon–Time
According to the phenomenon–time law
| [9] | Y. Zhu, L. Hong, Z. Yang, W. Yong, Conservation-dissipation formalism of irreversible thermodynamics, J. Non?Equilib. Thermodyn., 40(2015) 67-74.
https://doi.org/10.1515/jnet-2014-0037 |
| [10] | M. Esposito, Open questions on nonequilibrium thermodynamics of chemical reaction networks, Commun. Chem., 3(2020) 107. https://doi.org/10.1038/s42004-020-00344-7 |
| [21] | Shamohammadi, M. R. Yabaluei Khamesluei, B. Shamohammadi, The Law of Survival of Phenomena and Its Application in the Analysis of Dynamic Processes (2026).
https://doi.org/10.1007/s13201-025-02711-y |
[9, 10, 21]
, any extensive phenomenon can be expressed as:
where t is the local or coordinate time, and τ is the intrinsic or proper time.
In the simple case with constant flow characteristics and velocity, the phenomenon–time relationship reduces to:
Equilibrium Threshold
The boundary between unidirectional and bidirectional uptake is called the equilibrium threshold, denoted pT. This corresponds to the amount fully absorbed by the system.
Space as a Phenomenon
In mass–energy systems, space itself is an extensive quantity because it determines the geometric–mass capacity of the flux. Space can be represented as the product of effective flux dimensions or the integral over mass–energy depths. Thus, “space” can also be modeled as a phenomenon
.
Bending
In open systems, if the output–input ratio is constant and equal to one, the curve is linear. Any reduction or increase in this ratio induces bending of the curve
| [19] | Shamohammadi, N. Aghabozorgi, H. R. Motaghyan, A. Semnanian, Introducing the law of irreversibility in the dynamic equilibrium of mass, Case Stud Chem Environ Eng., 10(2) (2024) 100746. https://doi.org/10.1016/j.cscee.2024.100746 |
| [21] | Shamohammadi, M. R. Yabaluei Khamesluei, B. Shamohammadi, The Law of Survival of Phenomena and Its Application in the Analysis of Dynamic Processes (2026).
https://doi.org/10.1007/s13201-025-02711-y |
[19, 21]
.
Hence, the curve curvature directly reflects the dynamics of the phenomenon in time and space and represents the actual output relative to the input or local time.
2.1.7. Principle of Initial Irreversibility
According to the principle of initial irreversibility
| [9] | Y. Zhu, L. Hong, Z. Yang, W. Yong, Conservation-dissipation formalism of irreversible thermodynamics, J. Non?Equilib. Thermodyn., 40(2015) 67-74.
https://doi.org/10.1515/jnet-2014-0037 |
| [10] | M. Esposito, Open questions on nonequilibrium thermodynamics of chemical reaction networks, Commun. Chem., 3(2020) 107. https://doi.org/10.1038/s42004-020-00344-7 |
| [19] | Shamohammadi, N. Aghabozorgi, H. R. Motaghyan, A. Semnanian, Introducing the law of irreversibility in the dynamic equilibrium of mass, Case Stud Chem Environ Eng., 10(2) (2024) 100746. https://doi.org/10.1016/j.cscee.2024.100746 |
| [21] | Shamohammadi, M. R. Yabaluei Khamesluei, B. Shamohammadi, The Law of Survival of Phenomena and Its Application in the Analysis of Dynamic Processes (2026).
https://doi.org/10.1007/s13201-025-02711-y |
[9, 10, 19, 21]
, the beginning of any natural process requires the formation of an initial directed stage in which the evolution of the system follows a linear and asymmetric path with respect to time reversal. This initial directionality, independent of thermodynamic considerations, is considered the structural origin of the irreversibility of the process in its later stages.
The principle of initial irreversibility has two important differences from the law of thermodynamics: 1) it is independent of the unidirectional direction of change, and the direction of change can lead to a decrease or an increase in entropy; 2) it emphasizes the linearity of the process at the beginning of any natural interaction.
2.2. Conceptualization
2.2.1. Mass and Energy Processes in Open Systems
The phenomenon–time framework presented in this study is based on the assumption that system dynamics can be described by tracking the evolution paths of extensive quantities and how they are absorbed over time and space.
The goal of this framework is not to derive closed forms for all existing empirical relationships but to demonstrate that the general structure of these relationships—regardless of domain-specific details—can be mapped onto a unified phenomenon–time pattern.
To illustrate the proposed framework, two classical examples of open systems are considered: rainfall–runoff and energy–motion. These examples reveal the general pattern of extensive phenomenon behavior.
(i). Rainfall–Runoff
When precipitation begins over dry soil, the hydrological response can be divided into three distinct stages. In the first stage (0≤t≤T), all rainfall input is used for surface absorption, vegetation wetting, and storage in microtopography, with no runoff formation. This stage is inherently irreversible, and the entire input is stored as the initial uptake pT in the system. As time progresses, absorption capacity decreases, and part of the input becomes runoff, such that equilibrium uptake (pe) and residual output (pr) appear simultaneously (pr↔pe).
This behavior leads to a concave curve with a decreasing slope. Ultimately, under uniform precipitation and asymptotic conditions (t→∞), the total soil uptake capacity p
maxp_{\rm max}pmax is reached, and nearly all input converts to runoff. This pattern aligns with the general structure of phenomenon–time and phenomenon–phenomenon behavior in open systems
| [4] | L. A. Richards, Capillary conduction of liquids through porous mediums, Phys., 1(1931) 318-333.
https://doi.org/10.1063/1.1745010 |
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| [6] | I. Sharma, R. Singh, A. Verma, Modified NRCS-CN method for runoff modeling, J. Hydro Environ. Res., 44(2022) 35-52.
https://doi.org/10.1016/j.jher.2022.07.002 |
| [17] | Shamohammadi et al. (2023a), Presentation of a rainfall runoff retention model (3RM) based on antecedent effective retention, CivilEng, 4(3) (2023) 966-981.
https://doi.org/10.3390/civileng4030052 |
| [18] | Shamohammadi, M. Kadkhodahosseini, K. Ostad Ali Askari, New procedure to estimate soil field capacity based on double ring infiltration data, Ain Shams Eng. J., 14 (2023b) 102511.
https://doi.org/10.1016/j.asej.2023.102511 |
[4-6, 17, 18]
.
Equation 2 describes the two-stage process of natural phenomena in an open system:
(2)
(ii). Energy and Motion of a Body
For a body subjected to a constant force, the system’s dynamic response can similarly be divided into three stages. In the initial interval (0≤t≤T), all input energy is used to overcome static friction and stored as the initial uptake in the body–surface system. Once motion begins, the input energy is distributed between kinetic friction (p
e-) and the kinetic energy of the body (p
r-). At long times under a constant force, the system reaches uniform motion, and the input energy effectively converts into kinetic energy. This structure precisely follows the “initial uptake → equilibrium uptake ⇌ residual phenomenon” pattern and is consistent with experimentally observed behaviors in mechanical and thermodynamic systems
| [9] | Y. Zhu, L. Hong, Z. Yang, W. Yong, Conservation-dissipation formalism of irreversible thermodynamics, J. Non?Equilib. Thermodyn., 40(2015) 67-74.
https://doi.org/10.1515/jnet-2014-0037 |
| [10] | M. Esposito, Open questions on nonequilibrium thermodynamics of chemical reaction networks, Commun. Chem., 3(2020) 107. https://doi.org/10.1038/s42004-020-00344-7 |
| [11] | D. Jou, J. Casas?Vázquez, G. Lebon, Extended irreversible thermodynamics, Rep. Prog. Phys., 51(1988) 1105-1179.
https://doi.org/10.1088/0034-4885/51/8/002 |
| [13] | U. Lucia, G. Grisolia, Time, irreversibility, and entropy production, Entropy, 22(2020) 887.
https://doi.org/10.3390/e22080887 |
| [14] | I. Prigogine, Time, structure and fluctuations, Science, 201 (1978) 777-785. https://doi.org/10.1126/science.201.4358.777 |
[9-11, 13, 14]
.
The described pattern is observed not only in rainfall–runoff and mechanical motion but also in adsorption processes, chemical reaction kinetics, water infiltration in soil, biological growth curves, and learning curves. Empirical and analytical studies have demonstrated that these processes share a common general form
| [15] | S. M. Endres, Entropy production selects nonequilibrium states in multistable systems, Sci. Rep., 7(2017) 14437.
https://doi.org/10.1038/s41598-017-14485-8 |
| [16] | Shamohammadi, Z., Bustanian, M., Tavakol, H., Removing Cd (II) from water and wastewater by blowy sand; the effects of total hardness and pH, J. Desalination Water Treat., 51 (2013) 16-18. https://doi.org/10.1080/19443994.2012.749365 |
| [17] | Shamohammadi et al. (2023a), Presentation of a rainfall runoff retention model (3RM) based on antecedent effective retention, CivilEng, 4(3) (2023) 966-981.
https://doi.org/10.3390/civileng4030052 |
| [18] | Shamohammadi, M. Kadkhodahosseini, K. Ostad Ali Askari, New procedure to estimate soil field capacity based on double ring infiltration data, Ain Shams Eng. J., 14 (2023b) 102511.
https://doi.org/10.1016/j.asej.2023.102511 |
| [19] | Shamohammadi, N. Aghabozorgi, H. R. Motaghyan, A. Semnanian, Introducing the law of irreversibility in the dynamic equilibrium of mass, Case Stud Chem Environ Eng., 10(2) (2024) 100746. https://doi.org/10.1016/j.cscee.2024.100746 |
| [20] | Shamohammadi, S., Basics of modern modeling and expansion of the relativity theory of time in classical physics, Appl. Water Sci., 14(2024) 227.
https://doi.org/10.1007/s13201-024-02263-7 |
[15-20]
.
Figure 2 shows the general shape representation of the phenomenon-phenomenon curves (A) and phenomenon-time curves (B) based on experimental data and analytical models reported in
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https://doi.org/10.1016/S0032?9592(98)00112-5 |
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https://doi.org/10.1016/j.jhazmat.2020.122156 |
| [13] | U. Lucia, G. Grisolia, Time, irreversibility, and entropy production, Entropy, 22(2020) 887.
https://doi.org/10.3390/e22080887 |
| [14] | I. Prigogine, Time, structure and fluctuations, Science, 201 (1978) 777-785. https://doi.org/10.1126/science.201.4358.777 |
| [15] | S. M. Endres, Entropy production selects nonequilibrium states in multistable systems, Sci. Rep., 7(2017) 14437.
https://doi.org/10.1038/s41598-017-14485-8 |
| [16] | Shamohammadi, Z., Bustanian, M., Tavakol, H., Removing Cd (II) from water and wastewater by blowy sand; the effects of total hardness and pH, J. Desalination Water Treat., 51 (2013) 16-18. https://doi.org/10.1080/19443994.2012.749365 |
| [17] | Shamohammadi et al. (2023a), Presentation of a rainfall runoff retention model (3RM) based on antecedent effective retention, CivilEng, 4(3) (2023) 966-981.
https://doi.org/10.3390/civileng4030052 |
| [18] | Shamohammadi, M. Kadkhodahosseini, K. Ostad Ali Askari, New procedure to estimate soil field capacity based on double ring infiltration data, Ain Shams Eng. J., 14 (2023b) 102511.
https://doi.org/10.1016/j.asej.2023.102511 |
| [19] | Shamohammadi, N. Aghabozorgi, H. R. Motaghyan, A. Semnanian, Introducing the law of irreversibility in the dynamic equilibrium of mass, Case Stud Chem Environ Eng., 10(2) (2024) 100746. https://doi.org/10.1016/j.cscee.2024.100746 |
| [21] | Shamohammadi, M. R. Yabaluei Khamesluei, B. Shamohammadi, The Law of Survival of Phenomena and Its Application in the Analysis of Dynamic Processes (2026).
https://doi.org/10.1007/s13201-025-02711-y |
| [22] | Loschmidt, J., On the state of thermal equilibrium, Entropy, 17(2015) 1039. https://doi.org/10.3390/e17031039 |
[1, 2, 7, 13-19, 21, 22]
.
2.2.2. Limitations of Traditional Coordinate Axes
Loss of the true spacetime substrate
In the Cartesian framework, the precise value of pin=vpt is inherently undefined. In these plots, the time axis is merely horizontal, providing no information about the flow path, input velocity vp, or the geometric–physical space. Consequently, the velocity vector is effectively removed from the model, and the system’s dynamic behavior is incompletely represented.Even in cases where the input is implicitly considered in models, it lacks a defined geometric location and a traceable evolution path; as a result, explicit and continuous enforcement of the conservation law along the process is impossible.
Inability to apply the conservation law
In both three- and four-dimensional coordinate systems, even if one assumes that the conservation law holds in an open-system format,
the positions of outputs cannot be identified, the initial slope (dynamic initial condition) is not visible, and there is no equilibrium point or input–output reference to apply the conservation principle.
Consequently, models derived from such plots are typically empirical, trial-and-error, non-generalizable, and inconsistent with conservation laws.
Fundamental Corrections
Recent studies have shown that to properly model persistent phenomena, providing a comparable mathematical model that is capable of simulating natural data, five fundamental modifications are needed
:
1) Apply conservation laws in an open-system format (mass conservation is usually shown in a closed-system form).
2) Employ the phenomenon–time law, analogous to the relation L=ct in relativity.
3) Apply the principle of irreversibility.
4) Design experiments based on the phenomenon–time framework.
5) Modify traditional coordinate systems and introduce a new geometric–physical coordinate system.
6) Based on previous studies
| [17] | Shamohammadi et al. (2023a), Presentation of a rainfall runoff retention model (3RM) based on antecedent effective retention, CivilEng, 4(3) (2023) 966-981.
https://doi.org/10.3390/civileng4030052 |
| [18] | Shamohammadi, M. Kadkhodahosseini, K. Ostad Ali Askari, New procedure to estimate soil field capacity based on double ring infiltration data, Ain Shams Eng. J., 14 (2023b) 102511.
https://doi.org/10.1016/j.asej.2023.102511 |
| [19] | Shamohammadi, N. Aghabozorgi, H. R. Motaghyan, A. Semnanian, Introducing the law of irreversibility in the dynamic equilibrium of mass, Case Stud Chem Environ Eng., 10(2) (2024) 100746. https://doi.org/10.1016/j.cscee.2024.100746 |
| [20] | Shamohammadi, S., Basics of modern modeling and expansion of the relativity theory of time in classical physics, Appl. Water Sci., 14(2024) 227.
https://doi.org/10.1007/s13201-024-02263-7 |
| [21] | Shamohammadi, M. R. Yabaluei Khamesluei, B. Shamohammadi, The Law of Survival of Phenomena and Its Application in the Analysis of Dynamic Processes (2026).
https://doi.org/10.1007/s13201-025-02711-y |
[17-21]
, coordinate system modification is more fundamental than the other five items. The proposed coordinate system is introduced below.
2.2.3. Four-Dimensional System with L-Equilibrium Constraint
In this study, a four-dimensional coordinate system is proposed in which the L equilibrium axis plays a key role. According to this framework, the output vector p
out is the sum of three spatial components p
x, p
y, and p
z, and the input vector p
in defined according to the phenomenon–time law
| [8] | H. C. Öttinger, Nonequilibrium thermodynamics for open systems: GENERIC framework, Phys. Rev. E, 73(2006) 036126. https://doi.org/10.1103/PhysRevE.73.036126 |
| [9] | Y. Zhu, L. Hong, Z. Yang, W. Yong, Conservation-dissipation formalism of irreversible thermodynamics, J. Non?Equilib. Thermodyn., 40(2015) 67-74.
https://doi.org/10.1515/jnet-2014-0037 |
| [10] | M. Esposito, Open questions on nonequilibrium thermodynamics of chemical reaction networks, Commun. Chem., 3(2020) 107. https://doi.org/10.1038/s42004-020-00344-7 |
| [11] | D. Jou, J. Casas?Vázquez, G. Lebon, Extended irreversible thermodynamics, Rep. Prog. Phys., 51(1988) 1105-1179.
https://doi.org/10.1088/0034-4885/51/8/002 |
| [12] | D. Zhang, Q. Ouyang, Nonequilibrium thermodynamics in biochemical systems and its application, Entropy, 23(2021) 271. https://doi.org/10.3390/e23030271 |
| [13] | U. Lucia, G. Grisolia, Time, irreversibility, and entropy production, Entropy, 22(2020) 887.
https://doi.org/10.3390/e22080887 |
| [14] | I. Prigogine, Time, structure and fluctuations, Science, 201 (1978) 777-785. https://doi.org/10.1126/science.201.4358.777 |
| [21] | Shamohammadi, M. R. Yabaluei Khamesluei, B. Shamohammadi, The Law of Survival of Phenomena and Its Application in the Analysis of Dynamic Processes (2026).
https://doi.org/10.1007/s13201-025-02711-y |
[8-14, 21]
as pin=v
pt.
In the open system, the L axis is introduced as the conservation or equilibrium axis, dividing the coordinate plane into two symmetric regions: the first region represents the input values, and the second corresponds to the outputs.
This axis contains all points where the conservation law of the phenomenon holds and, in addition to maintaining input–output equilibrium, defines the dynamic boundary between output components p
T, p
e, and p
r (
Figure 2).
It is necessary to emphasize that the angle shown in this figure has a geometric-descriptive meaning and is used to show the application of the input-output equilibrium constraint in the coordinate space.
In
Figure 3, the units of measurement are shown in terms of the quantity being measured, for example, if the phenomenon is a mass quantity, the horizontal axis can be (seconds) (milligrams per second) and the vertical axis is shown in milligrams. But the L axis borrows its unit from the input and output quantities. Since the L axis is the balance axis, it is usually equal to 1, unless the horizontal axis is measured in time, in which case the balance axis unit is the same as the initial input velocity v
p. In this case, the L axis will rotate by α=45v
p depending on the value of v
p.
L-axis angle and its role in irreversibility analysis
The L axis is typically drawn at a 45∘ angle relative to the input and output axes. This geometry has two key effects in analyzing extensive and irreversible processes:
1) Transforming the principle of irreversibility into an exact mathematical form: When input and output belong to the same type of quantity (e.g., mass–mass or energy–energy), the 45∘ angle ensures that the L-axis scales for input and output are identical. This condition allows the initiation point of the bidirectional process and the equilibrium threshold pT to be geometrically and unambiguously determined.
2) Initial tangency of experimental curves: Many empirical curves of extensive processes converge toward the L-axis (the L-axis is tangent to the curve’s starting point). Therefore, assuming the terminal portion of the process curve is parallel to the horizontal axis, analytical expressions for the curve can be derived. Even when input is expressed as a function of time t, the L-axis, with an adjusted angle based on vp, can accurately model the starting point and initial path of the experimental curve.
3) This framework systematically enables the extension of irreversibility analysis and curve geometry to systems with heterogeneous quantities while maintaining mathematical accuracy and clarity for homogeneous cases.
Phenomenon–time mapping: From the L-axis geometry, the following relationship holds for any value of x:
Reminder: because the angle between the line L and the horizontal axis (A) is 45 degrees, it is proved that for each value of:
This relationship provides the basis for mapping between the time and phenomenon axes, allowing simultaneous dynamic analysis in both frameworks.
2.2.4. Mathematical Formulation of the Phenomenon–Time Model
To derive the mathematical model from the conceptual curve of
Figure 2, the conservation law of the phenomenon is first written:
But secondary acceptance is equal to:
Also, according to the law of time phenomena, 𝑝
𝑖𝑛=𝑣
𝑝𝑡 Therefore: Equation 4 can be written as a time phenomenon to model the reversible part as Equation (
5).
And after moving the parameters in Equation (
4), Equation (
5) is obtained.
To solve Equation (
5), it is sufficient to use the following two assumptions based on the conceptual model in
Figure 2.
The constant ksh is the transition characteristic.
To test hypotheses 6 and 7, since the curve is a gradual change, it is sufficient to examine the time t for the two limits t→0 and t→∞. In this case, both sides of the equation are equal. In this case, by integrating equations (
6) and (
7) into equation (
5), the time phenomenon equation (
8) is obtained for the equilibrium part of the process.
(8)
But using Equation (
4), Equation (
8) can be written as Equation (
9), which is called the general equation of the phenomenon.
(9)
Equation (
9) can be converted to Equation (
10) based on the law of time phenomena.
(10)
Equation (
10) is called the universal principle equation of saturation dynamics.
Equation (
10) is called the phenomenon–phenomenon equation, representing a static slice of the dynamic model (Equation (
9)).
Equations (
9) and (
10) are expressed in terms of system acceptance. When expressed in terms of residual values, using Equation (
3), one obtains:
or
Substituting Equation (
9) into Equation (
11) gives the residual phenomenon:
(12)
Equation (
12) describes the residual phenomenon for a continuous and unlimited input flow. Studies have shown
that for an unlimited input p
in, this equation corresponds exactly to the runoff equation in hydrology (see
Table 2).
If the input pin is a finite source N0, then replacing pr with N(t)) yields:
(13)
Equation (
13) corresponds to the decay equation in chemical kinetics, also referred to in literature as the reactant depletion curve
.
In many processes, p
T is negligible; thus, Equation (
13) simplifies to:
(14)
Equation (
14) represents the half-life equation (see
Table 2), where N
0 is the total initial quantity and N(t) is the remaining quantity at time t.
3. Discussion
3.1. Geometric–Physical Framework and the L-Equilibrium Axis
The proposed framework is based on a four-dimensional manifold with the L-axis and the phenomenon–time law. Unlike classical Cartesian or Minkowski spacetime systems, this framework does not merely capture the instantaneous states of quantities; it models the evolution paths, fluxes, and input–output equilibrium of extensive quantities in open systems. The L-axis, as a geometric–structural constraint, aligns the input and output paths within a unified substrate and preserves the flow ratio:
It is important to emphasize that the ℓ axis of equilibrium should not be confused with conventional non-Cartesian coordinates or metric-based structures. The role of is to define a geometric constraint on the path of open systems, not to reformulate physical space in the classical sense.
3.2. Emergence of Diverse Empirical Structures from a Single Principle
The results indicate that many empirical equations across different fields—from hydrology and surface chemistry to reaction kinetics and substance half-life—follow a phenomenon–time structure. This structure consists of three components:
1) Primary irreversible acceptance (pT)
2) Secondary equilibrium acceptance (pe)
3) Uniform phenomenon flux (pin=vpt)
The combination of these components generates the general shape of empirical curves without requiring case-specific assumptions or fit-dependent parameters.
The application of this framework across different domains is summarized in
Table 1.Table 1.
Introduction of equilibrium dynamical models in different scientific fields based on the general phenomenon–time model . Dynamic model of the phenomenon | |
Scientific field | model | References |
Hydrodynamic infiltration(Law of Conservation of Spacetime) | | | [18] | Shamohammadi, M. Kadkhodahosseini, K. Ostad Ali Askari, New procedure to estimate soil field capacity based on double ring infiltration data, Ain Shams Eng. J., 14 (2023b) 102511.
https://doi.org/10.1016/j.asej.2023.102511 |
[18] |
Hydrology | Retemtion | | | [17] | Shamohammadi et al. (2023a), Presentation of a rainfall runoff retention model (3RM) based on antecedent effective retention, CivilEng, 4(3) (2023) 966-981.
https://doi.org/10.3390/civileng4030052 |
[17] |
Runoff | | | [17] | Shamohammadi et al. (2023a), Presentation of a rainfall runoff retention model (3RM) based on antecedent effective retention, CivilEng, 4(3) (2023) 966-981.
https://doi.org/10.3390/civileng4030052 |
[17] |
Surface chemistry | Adsorbtion | | | [20] | Shamohammadi, S., Basics of modern modeling and expansion of the relativity theory of time in classical physics, Appl. Water Sci., 14(2024) 227.
https://doi.org/10.1007/s13201-024-02263-7 | | [23] | Shamohammadi, S. Khajeh, M. Fattahi, R. Kadkhodahosseini, M. 2022. Introducing the new model of chemical adsorption for heavy metals by Jacobi activated carbon adsorbents, Iranian activated carbon and blowy sand. Case Stud Chem Environ Eng 6, (2022) 100220. |
[20, 23] |
Desorption | ) | | [23] | Shamohammadi, S. Khajeh, M. Fattahi, R. Kadkhodahosseini, M. 2022. Introducing the new model of chemical adsorption for heavy metals by Jacobi activated carbon adsorbents, Iranian activated carbon and blowy sand. Case Stud Chem Environ Eng 6, (2022) 100220. |
[23] |
Chemical kinetics | product | | |
reactant | | |
Motion and energy | | |
Hydrodynamic infiltration | | |
Hydrology(Rainfall–Runoff) | | | [17] | Shamohammadi et al. (2023a), Presentation of a rainfall runoff retention model (3RM) based on antecedent effective retention, CivilEng, 4(3) (2023) 966-981.
https://doi.org/10.3390/civileng4030052 |
[17] |
Surface chemistry | | |
Chemical kinetics (product) | | |
Motion and energy | | |
finite-state flow | | |
Half-life equation | | |
Table 2. List of abbreviations List of abbreviations List of abbreviations
Title | Parameter | Title | Parameter |
Friction energy loss threshold movement (Joules) | | Residual substance (mg/liter) | |
Maximum kinetic energy dissipated by friction (Joules) | | Maximum product substance (mg/liter) | |
Time Reparameterization | | Energy input to the system | |
Fixed initial speed (Phenomenon) | | speed | |
Transition characteristic | | length (in geometric space) | L |
All matter at time zero | | Time(mine) | |
Amount of remaining material versus time | | Amount of adsorption (mg / L) | * |
Product concentration in chemistry | | Maximum chemical absorption at the equilibrium threshold (mg/L) | |
Initial concentration (unlimited flow) | | Absorbent equilibrium capacity (mg / L) | qemax |
Adsorption equilibrium concentration (mg / L) | | speed of light | |
Initial concentration (limited source) | S | Adsorbent capacity (mg / L)* | |
Total Retention(mm) | | Characteristic time | |
Runoff depth | P | Special conversion rate | r |
rainfall(mm) | | Residual energy (potential) | |
Residual water (equilibrium) | | Product energy (kinetic) | |
Volumetric mass | | Residual energy (kinetic) | |
Infiltration depth(cm) | | Wasted energy (friction) | |
Volume | | Plant available water | |
Retention Equilibrium | | Equilibrium threshold Phenomenon | |
Permanent wilting point | | Maximum equilibrium Phenomenon | |
Accessible water threshold | | | |
Residual phenomenon | | Fixed initial speed (controlled) | |
Phenomenon | | Residual substance (mg/liter) | |
The phenomenon–time equations (
9) and phenomenon–phenomenon 10 are derived precisely from this general structure and show that seemingly separate models in different domains are all versions of the same basic dynamics. This is in complete agreement with the experimental findings reported in
| [16] | Shamohammadi, Z., Bustanian, M., Tavakol, H., Removing Cd (II) from water and wastewater by blowy sand; the effects of total hardness and pH, J. Desalination Water Treat., 51 (2013) 16-18. https://doi.org/10.1080/19443994.2012.749365 |
| [17] | Shamohammadi et al. (2023a), Presentation of a rainfall runoff retention model (3RM) based on antecedent effective retention, CivilEng, 4(3) (2023) 966-981.
https://doi.org/10.3390/civileng4030052 |
| [18] | Shamohammadi, M. Kadkhodahosseini, K. Ostad Ali Askari, New procedure to estimate soil field capacity based on double ring infiltration data, Ain Shams Eng. J., 14 (2023b) 102511.
https://doi.org/10.1016/j.asej.2023.102511 |
| [19] | Shamohammadi, N. Aghabozorgi, H. R. Motaghyan, A. Semnanian, Introducing the law of irreversibility in the dynamic equilibrium of mass, Case Stud Chem Environ Eng., 10(2) (2024) 100746. https://doi.org/10.1016/j.cscee.2024.100746 |
| [20] | Shamohammadi, S., Basics of modern modeling and expansion of the relativity theory of time in classical physics, Appl. Water Sci., 14(2024) 227.
https://doi.org/10.1007/s13201-024-02263-7 |
| [21] | Shamohammadi, M. R. Yabaluei Khamesluei, B. Shamohammadi, The Law of Survival of Phenomena and Its Application in the Analysis of Dynamic Processes (2026).
https://doi.org/10.1007/s13201-025-02711-y |
[16-21]
, where the general model
has been confirmed in domains such as rainfall-runoff, water infiltration, surface adsorption, chemical kinetics, and friction-motion.
3.3. Limitations of Existing Models and Advantages of the Proposed Framework
Systematic literature review reveals common conceptual limitations in classical models—e.g., SCS–CN in hydrology, soil–water interaction, surface chemistry, reaction kinetics, and energy–motion dynamics:
1) Lack of explicit input flux definition: The fundamental parameter pin=vpt is either neglected or only implicitly considered. Input evolution paths are generally undefined, and conservation laws are not explicitly enforced.
2) Incomplete modeling of irreversibility and equilibrium threshold: The initial irreversible stage pT, clearly observed in experimental data, is often overlooked or substituted by empirical parameters.
3) Limited predictive capability for system capacity: The maximum system capacity pmax=pT+pe,max typically requires heavy calibration and is poorly generalizable.
4) Non-differentiability and unstable simulation: Empirical models are often non-differentiable, preventing precise dynamic simulation.
The proposed framework addresses these limitations using three fundamental principles:
1) The phenomenon–time law to define the input flux substrate
2) Incorporation of the primary irreversibility principle as a general component
3) The L-axis geometric constraint to represent input–output equilibrium and the onset of the equilibrium regime
Thus, the phenomenon–time equation is not an empirical approximation but a natural consequence of the combination of conservation laws, manifold geometry, and general behavior of open systems.
3.4. Formalism Consistency Across Scientific Domains
The phenomenon–time and phenomenon–phenomenon equations are not restricted to physics or engineering. Empirical evidence shows the same structural form emerging in biological, geological, and informational systems. This broad applicability indicates that the base dynamics “primary acceptance + equilibrium acceptance” is a general feature of open systems under conservation laws, independent of the specific scientific domain. Parameter mapping requires domain-specific interpretation, but the underlying mathematical structure remains consistent.
3.5. System Capacity Interpretation and Scientific Implications
A key implication of the phenomenon–time framework is the ability to extract intrinsic system capacities—including pT, pe,max and pmax—from the geometric structure of the L-axis. These capacities are intrinsic geometric–physical quantities derived from the conservation law and flux structure rather than empirical parameters. This is particularly advantageous in low-data or scale-invariant scenarios, providing robust predictive capability beyond conventional empirical models.