Fluid Motion Research Articles

Bioinspired Multilayered Knitted Fabric with Directional Water Transport and Collection for Personal Sweat Management.

Effective sweat management fabric for sportswear facilitates sweat removal from the skin and elevates the comfort for human. However, when the body is in a strong hot and humid environment or after strenuous exercise, the sweat management fabric will be totally wetted and saturated quickly. As a result, excess sweat cannot be absorbed effectively by the garment, which creates obvious stickiness and heaviness. In this paper, a directional water transport and collection multilayered knitted fabric (DWTCF) is prepared by plasma pretreatment technology and screen coating. The treelike water transport network inspired from nature is designed in order to drive the liquid flow along the channels. By surface modification, branched hydrophilic flow paths are fabricated, and other regions are hydrophobic. As a demonstration, DWTCF has been injected with water to observe the liquid transport behavior. During the experiment, 76.7% liquid is collected by DWTCF, but there is just 0.06% collected by an ordinary knitted fabric. The weight increase of the ordinary fabric is 555.4% larger than that of DWTCF. Specifically, DWTCF utilizes the wetting and pressure-gradient-induced interfacial tension as well as the gravitational effect to facilitate the fluid motion along the hydrophilic channel, in addition to the capillarity present in the fabric structure. This study provides a new idea to develop directional water transport and collection fabric to solve the moisture absorption saturation problem of the fabric, especially for conditions requiring intense sweating.

Axisymmetric Slow Rotation of Coaxial Soft/Porous Spheres.

The steady low-Reynolds-number rotation of a chain of coaxial soft spheres (each with an impermeable hard core covered by a permeable porous layer) about the axis in a viscous fluid is analyzed. The particles may be unequally spaced, and may differ in the permeability and inner and outer radii of the porous surface layer as well as angular velocity. By using a method of boundary collocation, the Stokes and Brinkman equations for the external fluid flow and flow within the surface layers, respectively, are solved semi-analytically. The particle interaction effect increases as the relative gap thickness between adjacent particles or their permeability decreases, which can be significant as the gap thickness approaches zero. A particle's hydrodynamic torque is reduced (its rotation is enhanced) when other particles rotate in the same direction at equivalent or greater angular velocities, but increases (its rotation is hindered) when other particles rotate in the opposite direction at arbitrary angular velocities. For particles with different radii or permeabilities, the particle interaction has a greater effect on smaller or more permeable particles than on larger or less permeable particles. For the rotation of three particles, the presence of the third particle can significantly affect the hydrodynamic torques acting on the other two particles. For the rotation of numerous particles, shielding effects between particles can be substantial. When the permeability of porous layers is low, relative fluid motion is barely felt by the hard cores of the soft particles. The insights gained from this analysis on the effects of interactions among rotating soft particles may be of great importance in many physicochemical applications of colloidal suspensions.

Numerical study of aphron drilling crosser fluids coating layer incorporated blood with zinc oxide (ZnO) nanoparticles injected in esophagus

AbstractThis study aims to explore a novel cross model for peristaltic flow, which has not been previously addressed. The focus is on investigating the peristaltic flow of an incompressible nanofluid within a vertically uniform channel. The current model has application in drug delivery, biomedical engineering, lab on chip etc. Utilizing peristaltic flow for drug delivery systems in symmetric channels offers precise control over fluid motion, non‐Newtonian fluids, such as polymer solutions used in drug formulations, exhibit complex flow behavior that can be manipulated through peristaltic pumping mechanisms. This application has the potential to revolutionize targeted drug delivery, enhancing therapeutic efficacy and minimizing side effects. Studying peristaltic flow in symmetric channels for non‐Newtonian fluids offers interdisciplinary insights and innovative applications. Understanding fluid rheology, channel geometry, and peristaltic pumping can lead to novel strategies for fluid control, with implications for healthcare, biotechnology, and materials science advancements. To simplify the complex system of nonlinear partial differential equations governing the flow, we consider long wavelengths and low Reynolds numbers. Subsequently, we employ Shooting methods to solve this system of equations, providing a comprehensive evaluation of the numerical results for key parameters such as velocity, temperature, concentration, and pressure gradient. The findings are presented through graphical representations of significant flow parameters.

Preliminary investigations into human neurofluid transport using multiple novel non-contrast MRI methods.

We discuss two potential non-invasive MRI methods to study phenomena related to subarachnoid cerebrospinal fluid (CSF) motion and perivascular fluid transport, and their association with sleep and aging. We apply diffusion-based intravoxel incoherent motion (IVIM) imaging to evaluate pseudodiffusion coefficient, D*, or CSF movement across large spaces like the subarachnoid space (SAS). We also performed perfusion-based multi-echo, Hadamard encoded arterial spin labeling (ASL) to evaluate whole brain cortical cerebral blood flow (CBF) and trans-endothelial exchange (Tex) of water from the vasculature into the perivascular space and parenchyma. Both methods were used in young adults (N = 9, 6 F, 23 ± 3 years old) in the setting of sleep and sleep deprivation. To study aging, 10 older adults (6 F, 67 ± 3 years old) were imaged after a night of normal sleep and compared with the young adults. D* in SAS was significantly (p < 0.05) reduced with sleep deprivation (0.016 ± 0.001 mm2/s) compared to normal sleep (0.018 ± 0.001 mm2/s) and marginally reduced with aging (0.017 ± 0.001 mm2/s, p = 0.029). Cortical CBF and Tex were unchanged with sleep deprivation but significantly lower in older adults (37 ± 3 ml/100 g/min, 578 ± 61 ms) than in young adults (42 ± 2 ml/100 g/min, 696 ± 62 ms). IVIM was sensitive to sleep physiology and aging, and multi-echo, multi-delay ASL was sensitive to aging.

Implicit finite difference simulations for unsteady oscillating flow of Walters-B nanofluid with microbes using the Cattaneo–Christov model

The thermal importance of nanoparticles in different fields of engineering is still a developing issue that necessitates additional focused consideration. The suspension of non-Newtonian fluids with nonmaterials has various applications in areas such as enhanced thermal systems, energy processes, aerospace engineering, and chemical industries. Following such motivations, this work aims to analyze the heat and mass transfer flow of Walters-B nanofluid in the presence of microorganisms. The fluid motion is presumed to be nonsteady over a surface that undergoes periodic acceleration. The motivations for studying nanofluid’s oscillating flow are its use in effective mixing processes, combustion stability, and process efficiency. The text provides a detailed explanation of the saturation of porous media. A modified theory for heat and mass fluxes, known as the Cattaneo–Christov approach, suggests an extension in heat equations. Moreover, it supports the interaction of radiation phenomena for enhancing heat transfer. It is noteworthy that the entire problem is represented using extremely nonlinear partial differential equations (PDEs). The CFD study utilizing the renowned implicit finite difference method (FDM) has been effectively employed to propose a numerical solution for the problem. The numerical results are deemed valid and confirmed within certain limiting cases, based on the available data. The evaluation of velocity, skin friction coefficient, Nusselt number, and Sherwood number as a function of time has been demonstrated for various parameters. It is asserted that the wall shear force exhibited an oscillating pattern with a greater magnitude as a result of the viscoelastic parameter. The Nusselt number and Sherwood number exhibit slight acceleration as a result of changes in the Prandtl number and Schmidt number, respectively. The proposed model is specifically designed for use in heat exchangers, vibrational systems, compact designs, and vibration control.

Exploration of linear and exponential heat source/sink with the significance of thermophoretic particle deposition on ZnO-SAE50 nano lubricant flow past a curved surface

The present research focuses on exploring the impact of linear and exponential heat source/sink on double-diffusive MHD convective flow heat and mass transport of ZnO – SAE50 nano lubricants in an exponentially stretching curved sheet along with the effect of thermophoretic particle deposition. The heat transmission is considered to be caused by both radiation and convection. The mathematical modelling of the considered problem results in a coupled system of partial differential equations, using suitable similarity transformation variables these equations are reduced to a coupled non-linear system of ordinary differential equations and are solved numerically by adopting the finite difference method to obtain the solution for the field variables. The quantity and spatial distribution of linear heat sources/sinks affect the physical dynamics and optimum status of the entire system and the application of exponential heat sources/sinks can improve heat dispersion and energy efficiency in industrial operations such as nuclear reactors and steel production. The thermophoretic particle deposition parameter controls particle concentration by allowing particles to accumulate on surfaces or in specific areas of the fluid. A rise in Hartmann number causes a mechanical damping force to act in the opposite direction of the fluid motion, lowering the speed of the fluid in the curved sheet. The heat and mass transmission properties are analyzed through the Levenberg – Marquardt backpropagating algorithm and the correlation coefficient has ideal values of unity for training, validation, testing, and overall. In light of this, the anticipated behaviour of the LMNN-BPA indicated that the heat transfer profile numerical data and the network output are in good consensus.

A novel swiss-roll counterflow micro-combustor: Experimental investigation of methane-oxygen flame behavior over time

This study introduces a novel Swiss-roll micro-combustor design that employs a non-premixed counterflow flame for efficient and stable micro-combustion. This design addresses practical system challenges by (1) stabilizing the flame, (2) enhancing heat recovery and gas preheating, (3) aligning gas momentum with the exhaust, and (4) minimizing disruptive fluid motion within the channels. This research investigates the dynamic behavior and combustion characteristics of a methane-oxygen flame within the combustor across a range of equivalence ratios (1.50–3.38). A synergistic approach combining flame dynamics analysis, spectroscopy, and RGB image processing explores the interplay between flame temperature, strain rate, and equivalence ratio. The results demonstrate the effectiveness of the RGB method as a cost-efficient tool for predicting variations in C2∗ and CH∗ radicals and light-intensity radiations. While flame thickness and length exhibit complex dependencies on the fuel-to-oxygen ratio and wall temperature, specific radical emissions vary dynamically with the equivalence ratio. Notably, equivalence ratios of 1.94 and 2.26 exhibit minimal temporal variations in flame properties, suggesting optimal stability and predictability for practical applications. The investigated flame is classified as a “cool flame,” and efficiency declines with richer mixtures due to increased exhaust heat loss and incomplete combustion. This work paves the way for further micro-combustor design optimization and unlocks the potential of non-premixed counterflow flames in diverse micro-scale applications.

Coupled finite element analysis of the dynamics of poroelastic media considering the relative fluid acceleration

AbstractThis paper mainly discusses the dynamics of poroelastic media using the finite element analysis based on the u‐v‐p full formulation, where , , and p denote the solid displacement, relative fluid velocity with respect to solid velocity, and pore fluid pressure. It incorporates the effect of relative fluid acceleration with respect to solid acceleration on soil dynamic response. The ‐‐p formulation is first verified through the comparison with the analytical solution. After that, the response of one‐dimensional saturated soil column and two‐dimensional partially saturated soil layer subjected to vertical loading with different combinations of soil permeability and loading frequency are investigated using the analyses with the ‐‐p and ‐p formulations, based on which the effect of relative pore fluid motion is discussed and the differences in the soil response between two kinds of analysis approaches are examined. Results reveal that the rapid fluid flow has a pronounced effect on soil dynamics and the soil with a greater degree of saturation is more sensitive to the increase of loading frequency and soil permeability. The soil dynamic response can basically be divided into two main categories that represent insignificant and significant flow motion depending on loading frequency and soil permeability. Furthermore, despite vertical loading, horizontal soil response can also be affected by the large relative pore fluid flow when loading frequency and soil permeability are large. In addition, the simplified formulation can still be applicable to predict dynamics of poroelastic media in cases with high loading frequency and low soil permeability.

Visible fluid motion on manipulation as the new threshold for intraoperatively determined knee arthroplasty component loosening: ADelphi study.

There is a lack of a clear, uniform definition for intraoperatively assessed component loosening of a knee arthroplasty component, complicating the interpretation and interchangeability of results of diagnostic studies using an intraoperative observation as the reference test. The purpose of this study was to establish a consensus among specialised knee revision surgeons regarding the definition of intraoperatively determined loosening of total or unicondylar knee arthroplasty components. Utilising the Delphi consensus method, an international panel of highly specialised knee revision surgeons was invited to participate in a three-round process. The initiation of the first round involved the exploration of possible criteria for intraoperatively determined loosening with open questions. The second round focused on rating these criteria importance on a five-point Likert scale. For the third round, criteria that reached consensus were summarised in consecutive definitions for intraoperatively determined loosening and proposed to the panel. Consensus was established when over 70% of participants agreed with a definition for intraoperatively determined loosening. The 34 responding panel members described in total 60 different criteria in the first round of which 34 criteria received consensus in the second round. Summarising these criteria resulted in four different definitions as minimal requirements for intraoperatively determined loosening. Eighty-eight percent of the panel members agreed on defining a component as loose if there is visible fluid motion at the interface observed during specific movements or when gently applying direct force. This study successfully established a consensus using a Delphi method among knee revision surgeons on the definition of intraoperatively determined component loosening. By agreeing on the visibility of fluid motion as new definition, this study provides a standardised reference for future diagnostic research. This definition will enhance the interpretability and interchangeability of future diagnostic studies evaluating knee arthroplasty component loosening. Level V.

Two-Field Excitation for Contactless Inductive Flow Tomography.

Contactless inductive flow tomography (CIFT) is a flow measurement technique allowing for visualization of the global flow in electrically conducting fluids. The method is based on the principle of induction by motion: very weak induced magnetic fields arise from the fluid motion under the influence of a primary excitation magnetic field and can be measured precisely outside of the fluid volume. The structure of the causative flow field can be reconstructed from the induced magnetic field values by solving the according linear inverse problem using appropriate regularization methods. The concurrent use of more than one excitation magnetic field is necessary to fully reconstruct three-dimensional liquid metal flows. In our laboratory demonstrator experiment, we impose two excitation magnetic fields perpendicular to each other to a mechanically driven flow of the liquid metal alloy GaInSn. In the first approach, the excitation fields are multiplexed. Here, the temporal resolution of the measurement needs to be kept as high as possible. Consecutive application by multiplexing enables determining the flow structure in the liquid with a temporal resolution down to 3 s with the existing equipment. In another approach, we concurrently apply two sinusoidal excitation fields with different frequencies. The signals are disentangled on the basis of the lock-in principle, enabling a successful reconstruction of the liquid metal flow.

SPH study of scale effects of perforated caissons

The hydrodynamic characteristics of perforated caissons are significantly influenced by the viscous fluid motion near the perforations on the front wall. Consequently, models designed in accordance with the Froude similarity suffer from the scale effects. To investigate the scale effects, a Smoothed Particle Hydrodynamics (SPH) model is established, in which fluid motion is governed by the continuity and Navier-Stokes equations, and the solid boundaries are represented by the dynamic boundary particles. The convergence and reliability of the SPH model are examined by employing it to replicate two laboratory experiments. Subsequently, the SPH model is applied to the study of interactions between regular waves and perforated caissons with different length scales, porosities, and chamber length to wavelength ratios. This enables an analysis of the scale effects on the vorticity and velocity fields, wave reflection, and wave force. The findings indicate that a scaled-down model tends to underestimate flow field intensity and wave force amplitude, while overestimate the wave reflection coefficient.

Volumetric Measurements Of Particle-Wake Interactions

Research on freely falling particles has primarily focused on wake dynamics and vortex shedding of individual particles in quiescent flow. When these particles fall collectively, the wakes of surrounding particles alter the flow fields. Hence, we conducted volumetric experiments to investigate how the settling and wake dynamics of particles are affected by the wakes of other settling particles. Negatively buoyant 12 mm particles of (sphere, flat cuboid, circular and square cylinders) are first released individually into quiescent water. Then, the particles are released individually into the bulk wakes of 20 mono-dispersed particles. Using four high-speed cameras and LEDs, we simultaneously capture both 3D particle and fluid motions in the terminal velocity regime. The imaging domain measures 90 mm x 90 mm x 40 mm. Our results show that all trailing particles settling through the bulk wakes gain additional downward momentum from the turbulent wakes, falling faster than in the quiescent flow. Upstream of the particle, the vortices in the bulk wake interact with the developing shear layer along the particle. The wake downstream of the trailing particle also appears more chaotic than that in a quiescent flow.

Enhancing Accuracy In 3D Defocusing Particle Tracking Using 3D-Printed Ramp

Three-dimensional defocusing particle tracking velocimetry (3D DPTV) is an emerging tool for investigating fluid motion within microfluidic devices, where observation is typically limited to a single direction. This technique enables the reconstruction of 3D flow fields by analyzing the defocused particle images. The accuracy of 3D DPTV significantly relies on the collection of a proper calibration image stack containing particle images with precisely known defocus distances. One major challenge is to insert a microscale calibration target inside the microfluidic devices due to the small length scales of microfluidic devices. While the alternative approaches such as using tilted glass slides or conducting z-scans of particles fixed at the bottom wall, face several limitations. Here, we present the application of a two-photon polymerization (2PP) based method to manufacture a microscale reference ramp as the calibration target. We demonstrate the fabrication of a precise reference ramp structure that spans the desired calibration range to enhance accuracy in 3D defocusing particle tracking. We experimentally and computationally compare the result with the commonly employed methods to obtain the calibration image stack. The performance of the 2PP-based calibration ramps is compared with the z-scanning method using the General Particle tracking (GPTV). The results demonstrate that the z-scanning method underestimates the defocused distances compared to the ground truth provided by the ramp approach, with the error increasing as the defocused distance grows. The integration of microscale calibration targets using 2PP fabrication method offers a significant advancement in the reliability and accuracy of 3D DPTV measurements in microfluidic systems. By enabling precise, device-specific calibration, this approach can enhance the fidelity of flow field reconstructions, benefiting a wide range of microfluidic applications that rely on detailed velocity field information.

Numerical simulation and thermodynamic test analysis of plate heat exchanger based on topology optimization

Efficient heat transfer in PHEs relies on optimizing flow distribution to minimize thermal dead zones. Existing studies have predominantly focused on single-phase fluids as working media and employed density-based methods for structural optimization of microchannel heat exchangers at small scales. In this study, the Brinkman term from the porous media flow model is introduced in an innovative manner, along with the utilization of a material density interpolation model, which builds upon the density-based approach. A novel two-phase fluid topology optimization method is proposed, specifically tailored for large-scale PHE operating conditions, resulting in the successful design of a new PHE topology. To compare the performance of the two heat exchangers, finite element simulation, visualization experiments, and thermodynamic performance testing are conducted. The simulation results reveal that the heat transfer capacity of the topological PHE is 810 W with pressure drops of 18.8 kPa, while the dimple PHE exhibits heat transfer capacity of 652 W with pressure drops of 25.9 kPa. Compared to the dimple PHE, the topological PHE demonstrates 24.2 % improvement in heat transfer performance and 27.8 % reduction in pressure drop. The dimensionless comprehensive heat transfer coefficient (j/f) indicates that the overall performance of the topological PHE significantly surpasses that of the traditional PHE. Furthermore, the visualization experiment results demonstrate that the complex texture structure of the topological PHE effectively induces fluid motion, compelling the fluid to flow along the texture direction. This significantly mitigates the issue of uneven flow within the PHE, thus enhancing heat transfer efficiency. Specifically, the topological PHE exhibits inlet–outlet temperature difference of 10.3 °C and pressure drops of 11.2 kPa, while the dimple PHE shows inlet–outlet temperature difference of 6 °C and pressure drops of 12.9 kPa. The findings of this study provide guidance for future research endeavors aimed at evaluating potential solutions to advance heat transfer in PHEs and facilitate the implementation of thermal management strategies.

A dynamic flow fetal membrane organ-on-a-chip system for modeling the effects of amniotic fluid motion.

Fetal membrane (amniochorion), the innermost lining of the intrauterine cavity, surround the fetus and enclose amniotic fluid. Unlike unidirectional blood flow, amniotic fluid subtly rocks back and forth, and thus, the innermost amnion epithelial cells are continuously exposed to low levels of shear stress from fluid undulation. Here, we tested the impact of fluid motion on amnion epithelial cells (AECs) as a bearer of force impact and their potential vulnerability to cytopathologic changes that can destabilize fetal membrane functions. A previously developed amnion membrane (AM) organ-on-chip (OOC) was utilized but with dynamic flow to culture human fetal amnion membrane cells. The applied flow was modulated to perfuse culture media back and forth for 48h to mimic fluid motion. A static culture condition was used as a negative control, and oxidative stress (OS) condition was used as a positive control representing pathophysiological changes. The impacts of fluidic motion were evaluated by measuring cell viability, cellular transition, and inflammation. Additionally, scanning electron microscopy (SEM) imaging was performed to observe microvilli formation. The results show that regardless of the applied flow rate, AECs and AMCs maintained their viability, morphology, innate meta-state, and low production of pro-inflammatory cytokines. E-cadherin expression and microvilli formation in the AECs were upregulated in a flow rate-dependent fashion; however, this did not impact cellular morphology or cellular transition or inflammation. OS treatment induced a mesenchymal morphology, significantly higher vimentin to cytokeratin 18 (CK-18) ratio, and pro-inflammatory cytokine production in AECs, whereas AMCs did not respond in any significant manner. Fluid motion and shear stress, if any, did not impact AEC cell function and did not cause inflammation. Thus, when using an amnion membrane OOC model, the inclusion of a dynamic flow environment is not necessary to mimic in utero physiologic cellular conditions of an amnion membrane.

Transient Decrease in Cerebrospinal Fluid Motion Is Related to Cough-Associated Headache in Chiari I Malformation

Short-lasting cough-associated Headache (CAH) in patients with Chiari I Malformation (CMI) is believed to be due to transient worsening of CSF flow obstruction at the foramen magnum. We assessed changes in CSF flow in response to coughing in CMI patients with CAH and compared to those without CAH and healthy participants (HP) using real-time MRI. Seventeen CMI patients (12 with CAH, 5 without CAH) and 6 HP were prospectively assessed using real-time pencil-beam imaging (PBI) MR sequence. A 64-mm length PBI cylinder was placed at the cranio-cervical junction. CSF stroke volume (SVCSF) was assessed during resting, post-coughing and relaxation phases via a 90-second scan. SVCSF was measured at six levels at 5-mm intervals between 10 and 35 mm below the foramen magnum. During each phase, SVCSF was compared between CMI with and without CAH and HP and corrected for multiple comparisons. At multiple consecutive levels, post-coughing SVCSF was significantly lower in CMI with CAH compared to both CMI without CAH and HP (p <0.05). No differences in post-coughing SVCSF were seen between CMI without CAH and HP. At rest or relaxation phase, no differences in SVCSF were seen between patients with and without CAH but minimal differences were seen between CMI with CAH and HP. A decrease in CSF flow after coughing in CMI patients with CAH supports the notion that CAH is caused by transient worsening of CSF flow obstruction at the foramen magnum.

Turbulence, thermal pressure, and their dynamical effects on cosmic baryonic fluid

ABSTRACT We employ the IllustrisTNG simulation data to investigate the turbulent and thermal motions of the cosmic baryonic fluid. With continuous wavelet transform techniques, we define the pressure spectra, or density-weighted velocity power spectra, as well as the spectral ratios, for both turbulent and thermal motions. We find that the magnitude of the turbulent pressure spectrum grows slightly from $z=4$ to 2 and increases significantly from $z=2$ to 1 at large scales, suggesting progressive turbulence injection into the cosmic fluid, whereas from $z=1$ to 0, the spectrum remains nearly constant, indicating that turbulence may be balanced by energy transfer and dissipation. The magnitude of the turbulent pressure spectra also increases with environmental density, with the highest density regions showing a turbulent pressure up to six times that of thermal pressure. We also explore the dynamical effects of turbulence and thermal motions, discovering that while thermal pressure provides support against structure collapse, turbulent pressure almost counteracts this support, challenging the common belief that turbulent pressure supports gas against overcooling.

Dynamical behavior of liquid-filled rotors with axial motion

In the present study, the dynamical behavior of liquid-filled rotors with axial motion is investigated. Based on the differential equations of motion for ideal fluids, the fluid forces exerted on the rotor are obtained. Then, the Euler–Bernoulli beam theory is utilized to establish the governing equations of motion for the rotor system. By applying Hamilton's principle, the governing equation and the corresponding boundary conditions are derived. Furthermore, in order to solve the eigenvalue problem of the system, the extended Galerkin method is applied to discrete equations of motion for the rotor system. As a result, the system stability, divergence, and flutter instability are defined. Moreover, a comparative study is presented to verify the accuracy of the proposed model. Finally, the effects of liquid parameters on the dynamic characteristics of the rotor system are investigated in detail. The results show that for liquid-filled rotors with axial motion, the stability of the system depends on the liquid parameters, axial velocity, and spinning velocity.

Numerical study on nanofluidic transport mechanism in Ellis flow within curved channel comprising compliant walls subjected to peristaltic activity

Peristaltic movement of fluid flows has significant applications in biomedical engineering, medicine, human physiology, etc. Specifically, it is very useful to understand and cure the very common intestinal diseases in human beings. A number of theoretical and empirical models are used to analyze peristaltic movement. In this work, the peristaltic movement of nanofluid is modeled with a non-Newtonian Ellis fluid model in a curved channel with compliant wall properties. The effects of Brownian motion, thermophoresis, and nonlinear radiations are considered in the heat transfer for better thermal analysis. The mathematical modeling of the physical problem yields the nonlinear partial differential equations with boundary conditions. First, the governing partial differential equations are non-dimensionalized, and then the resultant system is simplified by using the assumptions of a small Reynolds number and long wavelength. Then the obtained boundary value problem of differential equations is solved with the built-in Mathematica command NDSolve. The accuracy and reliability of the adopted procedure are verified by comparing the computed results with the reported literature. The impacts of the pertinent parameters (Brownian motion, thermal radiation, mixed convection, and thermophoresis phenomenon) on thermal energy, velocity, concentration, heat transfer rate, and stress at the lower wall are analyzed both in qualitative and quantitative manners. This study revealed some interesting facts, such as the peristaltic-driven motion of nanoliquid is strongly influenced by wall properties (i.e., wall elasticity, mass density, and wall damping). In addition, the flow experienced more resistance in the case of larger wall damping, but larger wall elasticity and mass density provide favorable movement for fluid motion. In addition, mixed convection plays a vital role in heat transfer and nanoparticle concentration in the curved domain. In addition, the curved channel walls have a higher stress factor than straight-plane channels. The results of the current study are very useful to understand many biological phenomena, such as the peristaltic movement of liquid during dialysis, food movement through the intestine, etc.

Exploring the impact of compressibility on reconstructed porous materials: A numerical study

This study underscores fluid density's significance in CFD simulations for porous materials, addressing its impact on accuracy and computational efficiency. The paper proposes a tailored form of Navier-Stokes equations that accounts for fluid density's influence on CFD analyses of porous materials in industrial contexts, including cases where the solid phase is deformable. Numerical analyses demonstrate fluid density's significance (ρ≠constant) and explore the importance of the energy equation in governing equations. The energy equation is essential in setting up the governing equations, as it calculates thermal characteristic length based on cell temperatures. By examining various porous material samples, the study suggests a streamlined approach: employing a single coupled CFD-FEM simulation to directly determine each geometrical parameter. Additionally, the study investigates the capability to accurately simulate turbulent fluid motion at the pore scale and analyze the flow field characterization within porous media. Computational cost analyses underscore the advantages of coupled simulations, establishing their profitability over separate parameter-specific simulations.