Abstract
Keywords
Introduction
Peristalsis is a process of moving fluid along a channel by deforming the surface. It involves squeezing and relaxing a flexible vessel to push the fluid through it. This process occurs in the human body, for example, when blood and urine are transported from the kidney to the bladder by the contraction and expansion of muscles. Peristalsis is also used to transfer fluid that should not come into contact with the mechanical parts of a pump, such as radioactive, toxic, or corrosive fluids in nuclear reactors. The earliest study of peristalsis flow was probably done by Latham 1 for his MS thesis. Later, Shapiro et al. 2 improved the understanding of peristalsis by examining the effects of reverse flow and pumping waves. Following their contributions, a substantial study has been undertaken on various flow patterns. Hayat et al. 3 investigated peristaltic motion within an angled tube using a magnetized Williamson liquid while accounting for heat and mass transmission. Using nanotechnology, Abbasi et al. 4 looked at how hall current and entropy optimization affected peristaltic activity. Riaz et al. 5 scrutinized the peristaltic motion of nano-sized elements in a curved conduit within a porous media, accounting for second-order slip phenomena. The heat transfer phenomena on peristaltic transportation of the hydromagnetic flow of non-Newtonian fourth-grade fluid in a tapered asymmetric channel filled with porous media was inspected by Rafiq et al. 6 The significance of double-diffusivity convection and an inclined magnetic field on peristaltic propulsion of fourth-grade nanofluids through an inclined asymmetric channel was reported by Akram et al. 7 Khan et al. 8 investigated the impact of double-diffusive convection and inclined magnetic field in nanofluids on the peristaltic pumping of fourth-grade fluid in a non-uniform channel. Rafiq et al. 9 examined the mixed convective movement of magnetized couple stress fluid across a curved structure, utilizing the lubrication concept as a foundation. Kada et al. 10 researched the shear-dependent peristalsis movement of non-Newtonian liquid in a microchannel with ciliated edges. Shaheen et al. 11 examined metachronal waves within a ciliated porous channel, with an emphasis on Williamson liquid with viscous dissipation. The effect of homogeneous and heterogeneous reactions on the peristaltic blood transportation of electrically conducting Williamson fluid in an asymmetric microchannel under velocity slip conditions was reported by Abbas et al. 12 Recently, Reddy et al. 13 discussed the electro-osmotic flow of entropy generation analysis for peristaltic movement in a nanofluid with temperature-dependent viscosity under lubrication theory.
The study of non-Newtonian fluids has gained significant attention due to their relevance in various engineering and industrial applications.14–16 Examples of such fluids include coal-oil slurries, paints, clay suspensions, coatings, cosmetic products, grease, custard, and physiological liquids. The tangent hyperbolic fluid model is one such non-Newtonian model, widely used to describe shear-thinning behavior and the effect of normal stresses. This model employs the hyperbolic tangent function, often denoted as “tanh,” to capture the relationship between shear stress and shear rate. It is particularly useful for fluids that demonstrate either shear-thinning or shear-thickening behavior, where the viscosity changes with the shear rate. Unlike Newtonian fluids, whose viscosity remains constant regardless of the shear rate, non-Newtonian fluids such as hyperbolic tangent fluids exhibit variable viscosity, which can be accurately modeled using the tanh function. This allows researchers and engineers to better predict and simulate fluid behavior in various applications, including in the food industry, cosmetics, and polymer processing. Several studies have focused on the peristaltic flow of hyperbolic tangent fluids. Nadeem and Akram 17 discussed the peristaltic motion of tangent hyperbolic tangent fluid in an asymmetric channel under the lubrication approximation theory. The heat and mass transfer phenomena in peristaltic transportation of hyperbolic tangent fluid through a tapered channel were discussed by Abbas and Rafiq. 18 Naduvinamani et al. 19 investigated the peristaltic transport of hyperbolic tangent fluid in a tapered Asymmetric channel. The impact of electro-osmotic flow, radiation, and Joule heating through a porous medium on the peristaltic motion of tangent hyperbolic fluid in an endoscope with the assumptions of low Reynolds number and long wavelength was reported by Kotnurkar and Talawar. 20 Elogail 21 analyzed the peristaltic flow of a hyperbolic tangent fluid with variable viscosity and thermal conductivity through a vertical asymmetric channel under the lubrication approximation hypothesis. Naduvinamani and Guttedar 22 studied the two-dimensional peristaltic flow of a hyperbolic tangent fluid in an asymmetric channel through a porous medium, utilizing long wavelength and low Reynolds number assumptions. Bartwal et al. 23 investigated the impact of melting heat transfer on the stagnation point flow of an electrically conducting hyperbolic tangent fluid over a porous rotating disk. Additionally, Bartwal et al. 24 examined the effects of irreversibility on the stagnation point flow of electrically conducting tangent hyperbolic fluid over a permeable, stretchable rotating disk, considering viscous dissipation effects.
The phenomenon in which an electrically conducting fluid is propelled by an externally applied magnetic force is referred to as Magnetohydrodynamic (MHD). MHD finds significant applications in different fields, including industrial engineering, geophysics, and physiology. It plays a crucial role in inflammation, aerodynamic heating process, electrostatic precipitation, glass production, generators, tumor detection, paper production, cancer treatment, MRI, blood reduction, and ulcer therapy. Furthermore, the investigation of peristalsis in relation to heat transfer is important, particularly in light of its applications in medical procedures such as oxygenation and hemodialysis. In 1942, the discipline of MHD used in fluid dynamics was initially established by the esteemed physicist Alfvén. 25 He received the Nobel Prize in 1970 for his significant contributions to this field. In the same way, Abbas et al.26,27 investigated the influence of variable viscosity on the peristaltic movement of viscous fluid under lubrication approximation theory. The peristaltic transport of blood-based nanofluid comprising cylindrical-shaped Gold (Au) nanoparticles in a non-uniform tube under the influence of a magnetic field was analyzed by Ashraf et al. 28 Abbasi et al. 29 inspected the impact of entropy generation on the peristaltic motion of a hybrid nanofluid within a 2D asymmetric channel. Hussain et al. 30 investigated the impact of a magnetic field on the peristaltic motion of sisko fluid through a channel having sinusoidal walls.
The slip effect is a crucial factor that needs to be determined in peristalsis flow. It refers to the change in angle when fluids leave the pumping material. Due to their wide applications in physiology, slip-flow studies have become significant today. The fluid slip behaviors in peristalsis have important uses for the process of polishing internal cavities, polymer technology, and heart valves. Fluid slips against the walls due to surface wetness. Slippage on the flow of different configurations under various effects has been studied by various authors in the literature. For instance, Akram et al. 31 analyzed the impacts of slip constraints on the peristaltic motion of magneto-Prandtl nanofluid through an asymmetric channel under the influence of double-diffusive convection, which includes both thermal and concentration gradients. The peristaltic flow of Prandtl fluid in the presence of mixed convection across a curved channel under slip conditions was discussed by Zahir. 32 Gangavathi et al. 33 investigated the consequences of Hall as well as slip taking place on the peristaltic stream of a Jeffrey solution through a permeable middling within an inclined 2D strait below the extensive wavelength estimation. The entropy generation and thermal characteristics of a couple stress blood nanofluid on the peristaltic slip flow of gold nanoparticles being conveyed through an asymmetric channel through a porous medium were inspected by Thabet et al. 34 Kumar and Yadav 35 discussed the peristaltic flow of non-miscible couple stress and Newtonian fluids flowing through a horizontal channel filled with a porous material with slip boundary conditions under the impact of an inclined magnetic field. Kanwal and Khan 36 investigated the influence of slip constraints on the peristaltic flow of Walter’s B fluid through an asymmetric channel under the lubrication hypothesis. Furthermore, Chemical reactions are classified as homogeneous and heterogeneous reaction effects. During a uniform flow across a flat surface, homogeneous reactions were represented by cubic autocatalysis, and heterogeneous reactions were represented by a first-order chemical reaction. Chemical reactions between acid and metal, reactions in batteries, electrolytic cells, and corrosion are all examples of heterogeneous reactions. When compared to heterogeneous reactions, homogeneous reactions are theoretically simpler because the reacting product is determined solely based on the species characteristics. However, the heterogeneous reactions are still important in practice because they relate the product’s dependence on the nature of two or more different reactant molecules. The peristaltic motion of Prandtl nanofluid by considering the homogeneous–heterogeneous reaction under lubrication approximation theory was discussed by Hayat et al. 37 The comportments of homogeneous-heterogeneous reactions on the peristalsis transportation mechanism of the Rabinowitsch fluid model inside a flexible channel were reported by Imran et al. 38 Javed et al. 39 investigated the effect of homogeneous-heterogeneous reactions on the MHD peristaltic mechanism of Ellis fluid in a curved channel. Recently, the peristaltic flow of Johnson-Segalman fluid in a curved flow channel in the presence of a homogeneous-heterogeneous reaction was inspected by Zahir et al. 40
The research gap in existing studies lies in the insufficient consideration of slip effects on the walls of larger peristaltic channels, where velocity slip might typically be neglected. Most current models assume no-slip conditions, as these were generally deemed irrelevant for larger channels, especially in biomedical or industrial settings. However, in specific scenarios such as microfluidic systems, drug delivery channels, and biomedical devices like endoscopes, slip effects become crucial due to the fine scale of these systems and the precise control required over fluid movement. Additionally, while homogeneous and heterogeneous reactions have been studied independently in peristaltic flows, their combined effects under slip conditions remain underexplored, particularly in MHD flows of non-Newtonian fluids like the hyperbolic tangent fluid. The present study, therefore, addresses these overlooked aspects by investigating the combined influence of velocity slip and reaction effects on the peristaltic flow of hyperbolic tangent fluids in an asymmetric channel under magnetic fields. This model is relevant for applications requiring precise fluid control under electromagnetic influence, such as microfluidic drug delivery systems, where chemical reactions between drug carriers and biological fluids might significantly impact drug dispersion. In such systems, slip conditions on channel walls can influence drug distribution rates and flow efficiency, affecting treatment efficacy. Similarly, in chemical reactors or biomedical devices that handle viscous or shear-sensitive materials, both slip effects and reaction kinetics play a role in optimizing flow and ensuring efficient transport without excessive shear stress on the fluid. This study not only fills the research gap but also has significant implications for designing biomedical devices that rely on controlled peristaltic flow, enabling enhanced precision in therapeutic applications. The novelty of the problem is given in Table 1. The resulting nonlinear equations are solved using the lubrication theory approximation, which is particularly relevant for predicting physiological characteristics, such as blood flow dynamics. Analytical solutions for velocity, pressure gradient, streamlines, and concentration distributions are obtained using the regular perturbation technique. The influence of various parameters on these distributions is presented through graphical analysis. Additionally, the pressure rise per wavelength along the channel walls is computed numerically.
The novelty of the problem.
Mathematical modeling
Let us consider the peristaltic transport of electrically conducting tangent hyperbolic fluid in an asymmetric channel with systematically relaxing and contracting sinusoidal walls. The flow model is sketched in Figure 1. The mathematical flow problem is modeled under the following assumptions:
• The peristaltic flow of tangent hyperbolic fluid is considered.
• The width of the channel is taken
• The flow analysis is formulated using a Cartesian frame. Here
• The channel asymmetry is produced by choosing the peristaltic wave train on the walls to have different amplitudes and phase differences.
• The electrically conducting flow is referred to as the impact of magnetic force along
• Low magnetic Reynolds is considered. Induced magnetic and electric field contributions are neglected.
• The velocity slip conditions and homogeneous and heterogeneous reactions are deliberated.
• Long wavelength and small Reynolds number assumptions are taken for the simplification of the problem.

Flow configuration of the problem.
The wave geometry is characterized by the following expressions 17 :
In equations (1) and (2), the symbols
The fundamental equations of non-Newtonian tangent hyperbolic fluid are considered as follows19,22:
Where
The induced magnetic field is neglected by assuming a very small magnetic Reynolds number
where the effect of the electric field is absent (
where,
The model for homogeneous-heterogeneous interaction is defined as follows 38 :
Here, we emphasize a single, isothermal, and first-order chemical reaction on the surface of the catalyst. Therefore, for such considerations
where
The Cauchy stress and extra stress tensors for the tangent hyperbolic fluid are given by23,24:
Here
In which the second invariant strain tensor is designated by
The velocity field for an unsteady two-dimensional flow is considered to be:
Using equation (18), the component form of equations (4)–(8) are given as follows:
The slip condition allows for a non-zero fluid velocity at the boundary, meaning the fluid can slip along the surface. This condition is particularly relevant in microfluidic systems or situations where the boundary surface has special properties, such as low friction or porous structures. In the context of this study, incorporating slip at the sinusoidal walls reflects the realistic behavior of fluid flow in permeable or low-friction boundaries, common in biological systems and industrial processes. The slip condition allows for more complex and accurate modeling of flow near boundaries, especially in the presence of deformable or permeable walls. The slip velocity boundary conditions are32,33:
The conditions for homogeneous–heterogeneous reactions are represented by the following expressions 13 :
The relation between fixed and moving reference frames is designated as:
The physical relations utilized to convert the set of governing equations from (17) to (23) into their corresponding dimensionless form are listed below:
Where
It is assumed that diffusion coefficients
Utilizing equations (24) and (25) with stream functions
Removing the term of pressure gradient from equations (27) and (28), one obtains
The appropriate boundary constraints are:
Where
The flow rate can be calculated as
where
Method of solution
The significance of the perturbation method is well established in the literature for its ability to provide an approximate analytical solution to nonlinear problems. The outcomes reported for the other comparatively sophisticated approximate analytical methods to nonlinear problems have decent accuracy, but they are more difficult in applications and analysis than perturbation methods. Thus, for many years, the relative simplicity and high precision in the limitation of small parameters have made perturbation methods fascinating tools among the most frequently utilized approximate analytical procedures. Perturbation methods usually use convenient mathematical formulations to provide accurate outcomes for small perturbation parameters. Therefore, the method of perturbation has been implemented to acquire the expressions for velocity, pressure gradient, and concentration for small values of the Weissenberg number for equation (27) and homogeneous parameter
Substituting equation (33) in equations (27)–(31) and repositioning the exponents of
Zeroth order system
with boundary conditions
First order system
with boundary conditions
Solutions for the system of zeroth order
The solutions of equations (32)–(34) with surface conditions (35) are given by
Solutions for the system of first-order
The solutions of equations (32)–(34) with surface conditions (35) are given by
The non-dimensional pressure rise over one wavelength
The values of the constants in zeroth and first-order solutions can be found via MATHEMATICA software.
Results and discussion
This portion characterizes the impacts of sundry parameters on the fluid velocity, pumping characteristics, and fluid temperature and streamlines through graphical outcomes. The expression

Comparison of the limiting case of the present study with the results of Naduvinamani and Guttedar. 22
Figure 3(a) to (c) displays the deviations in velocity profile

Velocity profile
Figure 4(a) to (c) shows the deviation in pressure gradient

Pressure gradient

Pressure rise
Figure 6(a) and (b) depicts concentration profile deviations concerning the homogeneous parameter

Concentration profile
Trapping is an intriguing phenomenon in peristaltic flow, where a fluid bolus forms due to the contraction and expansion of flexible walls, carried along by peristaltic waves. Figures 7(a) and (b) to 9(a) and (b) illustrate the effect of various parameters on trapping through contour plots in the no-slip condition. Figure 7(a) and (b) illustrates the effects of varying the magnetic parameter

Contour plots for distinct values of the magnetic parameter

Contour plots for distinct values of the Weissenberg number

Contour plots for distinct values of the power law index parameter

Contour plots for distinct values of the magnetic parameter

Contour plots for distinct values of the Weissenberg number

Contour plots for distinct values of the power law index parameter
Conclusions
This study presents an in-depth analysis of the peristaltic flow of an electrically conducting hyperbolic tangent fluid through an asymmetric channel, emphasizing the unique impacts of slip and reaction effects. The lubrication approximation theory is utilized to simplify the normalized equations. The perturbation solutions for the flow fields are obtained and impacts of dissimilar parameters on the flow fields are inspected through graphs. In the future, we can extend this work by adding various models like the Casson fluid model, the Jeffrey model, and the Buongiorno fluid model with more effects like mixed convection, bioconvection, and joule heating. We are assured that our current investigations are significantly applied to numerous mechanisms like cancer therapy, solar physics, the chemical industry, hyperthermia, the petroleum industry, and the recovery of targeted human cells of drugs. The summarized achievements of the current contribution are:
• The velocity profile increases in the upper half of the channel and decreases in the lower half of the channel with an increase in Weissenberg number. The increase in velocity in the upper half of the channel and the decrease in the lower half provide insight into asymmetric flow behavior, which is critical for accurately modeling non-Newtonian fluids in biological systems, such as blood or other physiological fluids.
• Slip conditions significantly influence the velocity profile and enhance overall flow efficiency, particularly in applications where no-slip conditions are typically assumed. Results demonstrate that under slip conditions, the fluid velocity is consistently higher compared to no-slip cases. This finding is relevant for applications that involve high-viscosity fluids, where channel wall adherence often impacts flow efficiency. Incorporating slip conditions in peristaltic flow designs could, therefore, optimize fluid transport processes in both medical devices and industrial applications.
• The pumping rate increases in the retrograde pumping region and decreases in the augmented pumping region by increasing the values of the magnetic parameter. The effects of the magnetic parameter on the pumping rate underscore the importance of electromagnetic fields in controlling flow dynamics, which could be valuable for designing more precise control mechanisms in magnetohydrodynamic (MHD) flows.
• Both homogeneous and heterogeneous reactions exhibit pronounced impacts on concentration profiles. The homogeneous reaction parameter is shown to increase concentration distribution, which is critical for applications requiring controlled substance diffusion, such as in drug delivery systems. Additionally, the opposing effects of homogeneous and heterogeneous reactions on the concentration field highlight an effective mechanism for fine-tuning peristaltic flow in biomedical contexts, where targeted delivery and precise fluid manipulation are essential.
• The trapped bolus number is enhanced by enhancing the value of the Weissenberg number. The discovery that the trapped bolus number increases with the Weissenberg number has potential implications for designing medical devices, particularly for managing conditions involving bolus trapping in the gastrointestinal or cardiovascular systems.
• The interaction between slip conditions, reaction effects, and the Weissenberg number offers a new perspective for designing peristaltic pumps. By carefully adjusting these parameters, engineers can optimize fluid movement and concentration distributions within channels. This knowledge contributes to improved models for peristaltic systems, supporting enhanced performance in applications ranging from drug delivery to gastrointestinal tract simulations.
Limitations of the study
• One of the primary limitations of this study is the use of the lubrication theory approximation, which, while suitable for predicting certain physiological flows like blood dynamics, restricts the analysis to low Reynolds number flows and long-wavelength assumptions. This limits the applicability of the results to higher Reynolds number scenarios, where inertial effects become more significant.
• Additionally, the study assumes an electrically conducting hyperbolic tangent fluid, which, although useful for capturing non-Newtonian fluid behavior, simplifies the complex rheology of actual biological fluids such as blood. The chosen model may not account for all aspects of real-world non-Newtonian behavior, particularly in more extreme conditions, which could affect the generalizability of the findings.
• Another limitation is the assumption of steady-state flow conditions. In practice, physiological flows are often transient, and this study does not capture time-dependent variations that could provide a more comprehensive understanding of flow behavior.
• Moreover, the homogeneous and heterogeneous reactions considered in the study are modeled under ideal conditions, without accounting for possible variations in reaction kinetics or external influences, which may affect the accuracy of the concentration distributions predicted.
• These limitations suggest that while the results provide valuable insights, they should be interpreted with caution when applying them to more complex or dynamic systems. Future studies could address these limitations by incorporating more detailed fluid models, transient analysis, and broader parameter ranges.
