Sinusoidal Microchannels Research Articles

Dielectrophoretic motion of a red blood cell in a microfluidic environment: Insights from numerical simulations

This research delves into the dielectrophoresis (DEP) behavior of a biological cell within a sinusoidal-shaped microchannel utilizing the Maxwell stress tensor (MST) theory. A red blood cell (RBC), immersed in a viscoelastic fluid, is studied considering the Oldroyd-B model. The study aims to fill a gap in the literature by examining the DEP characteristics of RBC in a realistic geometric configuration and fluid environment, bridging the divide between theoretical modeling and practical application. This work uniquely explores the DEP behavior of an RBC within a sinusoidal microchannel in the presence of a viscoelastic flow regime, which simulates plasma properties, marking a novel contribution to the field. The two-dimensional numerical model incorporates the finite element method to accurately simulate the DEP effect and describe the behavior of the viscoelastic fluid. Validation results confirm the accuracy of the MST model. Crucially, numerical findings highlight the strong dependence of DEP force on electric potential and fluid permittivity. As a consequence of their heightened levels, there is an associated increase in both the DEP force and velocity. While the augmentation of fluid viscosity merely results in a deceleration of DEP velocity. The study provides valuable insights into the interplay between physical parameters and particle behavior, paving the way for advancements in microfluidic particle manipulation techniques.

Asymmetrical Obstacles Enable Unilateral Inertial Focusing and Separation in Sinusoidal Microchannel

Inertial microfluidics uses the intrinsic fluid inertia in confined channels to manipulate the particles and cells in a simple, high-throughput, and precise manner. Inertial focusing in a straight channel results in several equilibrium positions within the cross sections. Introducing channel curvature and adjusting the cross-sectional aspect ratio and shape can modify inertial focusing positions and can reduce the number of equilibrium positions. In this work, we introduce an innovative way to adjust the inertial focusing and reduce equilibrium positions by embedding asymmetrical obstacle microstructures. We demonstrated that asymmetrical concave obstacles could break the symmetry of original inertial focusing positions, resulting in unilateral focusing. In addition, we characterized the influence of obstacle size and 3 asymmetrical obstacle patterns on unilateral inertial focusing. Finally, we applied differential unilateral focusing on the separation of 10- and 15-μm particles and isolation of brain cancer cells (U87MG) from white blood cells (WBCs), respectively. The results indicated an excellent cancer cell recovery of 96.4% and WBC rejection ratio of 98.81%. After single processing, the purity of the cancer cells was dramatically enhanced from 1.01% to 90.13%, with an 89.24-fold enrichment. We believe that embedding asymmetric concave micro-obstacles is a new strategy to achieve unilateral inertial focusing and separation in curved channels.

Optimized design of droplet micro-mixer with sinusoidal structure based on Pareto genetic algorithm

Mixing is one of the important steps in biological and chemical reactions and assays. In this paper, we numerically simulate the droplet generation and dynamic mixing in a double T-junction microchannel and optimize the geometry of the sinusoidal microchannel using a Pareto multi-objective genetic algorithm to provide important reference values for the design of efficient and integrated microfluidic chips. We choose two parameters related to the geometry of the sinusoidal microchannel as design variables, and use the average concentration difference within the droplet and the average pressure drop within the microchannel as two objective functions to explore the effects of design variables on the objective functions. The Latin hypercube sampling approach is used as an experimental design tool for parametric studies in design space, and it is used to choose design points in the design space. We employ proxy modeling of response surface functions to approximate the objective function. The Pareto optimal frontier of the micro-mixer is obtained using the Pareto genetic algorithm and the optimal solution set is classified using K-means clustering, from which representative design variables are chosen. The optimal set of solutions optimized with the Pareto genetic algorithm ensures the mixing quality while taking into account the pressure drop inside the microchannel. We also found two important factors affecting the mixing quality. (1) The contraction of the channel cross-section leads to alternating deformation of the droplets and enhances the mixing inside the droplets. When the droplet moves inside the microchannel, the channel cross-section alternately contracts and expands, changing the droplet to undergo alternate deformation, which changes the original internal circulation within the droplet and enhances the mixing inside the droplet. (2) Under the action of centrifugal force, the Dean vortex is generated, which enhances the mixing inside the droplet. The Dean vortex is generated when droplets move inside the curved channel. The Dean vortex causes asymmetric circulating flow inside the droplet, which increases the contact area of the fluid and thus significantly improves the mixing efficiency.

Microchannel structure design for hydrogen supply from methanol steam reforming

A methanol steam reforming-based microreactor is an extraordinary setup for hydrogen supply; nevertheless, the heat transfer capability and flow resistance of the microreactor may be restricted by each other, which calls for further structure design and investigation. To comprehensively improve the performance of a direct microchannel (DM) with the implementation of on-board hydrogen supply, the concepts of sinusoidal- and dimple-structured microchannels are synchronously introduced. Four types of microchannels for methanol steam reforming (MSR) are studied: direct microchannel (DM), direct microchannel with dimples (DMD), sinusoidal microchannel (SM), and sinusoidal microchannel with dimples (SMD). The influence of microchannel structure on the reformer’s flow and heat transfer properties is evaluated by Nusselt number, resistance coefficient, and heat transfer efficiency factor using numerical simulation. Results show that the SMD is the optimal structure. Moreover, the effects of reaction temperatures, methanol feeding fluxes, and steam/CH3OH mole ratios on the MSR performance are experimentally investigated. The effect of microchannel structures on the hydrogen production performance is also explored to validate the numerical simulation results. It is revealed that the integrated structure with both sinusoidal waves and dimples exhibited the best performance, demonstrating enhancements in heat and mass transportation as well as excellent H2 production capacity.

Transport Phenomenon of Simultaneously Developing Flow and Heat Transfer in Twisted Sinusoidal Wavy Microchannel under Pulsating Inlet Flow Condition

Heat transfer operations in microchannel are of special relevance in designing micro-devices involving accumulation of high heat flux. The current study explores simultaneously developing, unsteady laminar flow inside a twisted sinusoidal wavy microchannel and heat transfer involved. A square cross-sectioned channel is taken for the study. The channel is wavy in nature as well as twisted about the flow axis. The modified geometry helps in enhancing out of plane mixing of the fluid and formation of recirculation inside the flow. The evaluation is performed for a Reynolds number range of 1–100. A sinusoidal (varying with time) normal velocity component is employed at the inlet. The study was conducted over a range of pulsation amplitude and frequency. To solve the governing equations, a finite volume based method was employed. The Nusselt number data shows significant enhancement for the sinusoidal inlet velocity as compared to that of a steady case. In terms of pressure drop, the proposed design shows that at different frequencies and amplitudes, it can keep the pressure drop within admissible limits. Entropy generation is used as the measure of dissipated energy. Performance in terms of entropy generation is also reported.

Role of gradients and vortexes on suitable location of discrete heat sources on a sinusoidal-wall microchannel

The idea of using the compact device with higher heat transfer potential has encouraged researchers to use microchannels. Creating sinusoidal walls is a technique leading to better effectiveness and smaller size. In this study, the effects of discrete heat sources location on heat transfer and pressure drop are investigated, using graphene nanoplatelets/water inside a sinusoidal microchannel. For this, discrete heat sources are installed in a smooth microchannel (layout A) and compared with two sinusoidal-wall microchannels. In layouts B and C, the heating sources are installed above the convergent/diverging sections, respectively. Since the velocity and temperature gradients are higher in the converging region, the heat exchange and pressure drop for layout B are greater than other ones. In other words, installing heating sources in these regions with high-temperature gradient has a more obvious positive efficacy on heat exchange. For the best layout (B), although the heat exchange compared to the base layout (A) is 37.5% higher, the pressure drop and entropy generation are higher by 79% and 35.2%, respectively. By introducing a new figure of merit (FOM), it is found that layout B is in the desirable zone.

Inertial Microfluidic Purification of Floating Cancer Cells for Drug Screening and Three-Dimensional Tumor Models.

Floating cancer cells can survive the programmed death anoikis process after detaching from the extracellular matrix for the anchorage-dependent cells. Purification of viable floating cancer cells is essential for many biomedical studies, such as drug screening and cancer model development. However, the floating cancer cells are mixed with dead cells and debris in the medium supernatant. In this paper, we developed an inertial microfluidic device with sinusoidal microchannels to continuously remove dead cells and debris from viable cells. First, we characterized the differential inertial focusing properties of polystyrene beads in the devices. Then, we investigated the effects of flow rate on inertial focusing of floating MDA-MB-231 cells. At an optimal flow condition, purification of viable cells was performed and the purity of live cells was increased significantly from 19.9% to 76.6%, with a recovery rate of 69.7%. After separation, we studied and compared the floating and adherent MDA-MB-231 cells in terms of cell proliferation, protrusive cellular structure, and the expression of cyclooxygenase (Cox-2) which is related to epithelial-mesenchymal transition (EMT) changes. Meanwhile, drug screening of both floating and adherent cancer cells was conducted using a chemotherapeutic drug, doxorubicin (Dox). The results revealed that the floating cancer cells possess 30-fold acquired chemoresistance as compared to the adherent cancer cells. Furthermore, a three-dimensional (3D) double-cellular coculture model of human mammary fibroblasts (HMF) spheroid and cancer cells using the floating liquid marble technique was developed.

Analysis of friction interfaces with sinusoidal microchannels and the hybrid lubrication mechanisms of a tribo-film

The tribological behavior of Ti-alloys is crucial for increasing the service life and improving their usage accuracy of aero/avia-components. In this study, the friction interfaces covered with sinusoidal microchannels filled with SnAgCu, graphene, and Al2O3 were successfully prepared using high-temperature infiltration and laser additive manufacturing. The tribological behaviors, which were measured using the MFT-5000 tribometer of a Ti-(SnAgCu-Al2O3-Graphene), were better than those of the Ti-alloy, Ti-SnAgCu, Ti-(SnAgCu-Al2O3), and Ti-(SnAgCu-Graphene). The low-hardness tribo-film acted as a new-style friction interface during wear and yielded good lubrication. Excellent lubrication of a tribo-film was mainly essential for SnAgCu plastic deformation, inter-lamellar separation of multilayer graphene, and rolling-sliding mixture of spherical Al2O3. This was also attributed to the coordinating functions of SnAgCu-Al2O3, SnAgCu-Graphene, and SnAgCu-Al2O3-Graphene.

Investigation of the preparation and tribological behavior of a frictional interface covered with sinusoidal microchannels containing SnAgCu and Ti3SiC2

Tribological behavior of 37NbCrCo steel is a key factor with regard to the service life of the gearing systems. We prepared the frictional interfaces covered with sinusoidal microchannels in 37NbCrCo material, using laser additive manufacturing. Subsequently, lubricants of SnAgCu and Ti3SiC2 were filled into the microchannels using high-temperature infiltration. On a MFT-5000 tribometer, tribological behaviors of 37NbCrCo–SnAgCu–Ti3SiC2 were superior to 37NbCrCo and 37NbCrCo–SnAgCu. Moreover, the Ti3SiC2 was wrapped into the SnAgCu alloys to ensure the formation of soft tribo-film on the high-hardness supporting layer. The following factors were responsible for the excellent friction and wear behaviors, namely: the Ti3SiC2-induced the formation of the tribo-film, plastic deformation of SnAgCu, the rolling friction of Ti3SiC2, and their cooperation functions.

Numerical Investigation of Heat Transfer and Fluid Flow Characteristics in Circular Wavy Microchannels with Sidewall Rib

AbstractPurpose: Numerical investigation was carried out to study the hydro-thermal characteristics in circular wavy microchannels (CWMCs) with sidewall rib. Thermal resistance and pressure drop penalty were compared with sinusoidal wavy microchannels (SWMCs) design. Parametric study on sidewall rib was also carried to minimize the pressure drop penalty and to achieve lower thermal resistance. Introducing sidewall rib in the CWMCs leads to the formation of more Deans vortices. This leads to an effective fluid mixing and augments the convective heat transfer. Design methodology/approach: A computational solid domain was created in SOLIDWORKS and the fluid domain was produced by circular arc profile for the entire length of heat sink. 3-D numerical investigation was carried out using ANSYS FLUENT software. Created computational domain was imported into ANSYS WORKBENCH. Meshing was executed in ANSYS mesh module. The computational domains were meshed using hexahedral elements adopting match control on both sides of microchannel (MC). The numerical investigation was carried out in the Re range from 100 to 300 with constant heat flux (50 W/cm2) applied at the bottom of the channel. Heat transfer and fluid flow characteristics were explained with velocity vectors, velocity contours and temperature contours. Findings: From numerical studies, it is concluded that CWMC with sidewall rib width (0.15 mm) leads to 33.6 % lower thermal resistance than SWMC with pressure drop penalty. Originality/Value: Present study is useful to identify the optimum deign to augment the heat dissipation performance of microchannel heat sink.

Numerical Prediction of Heat Transfer and Fluid Flow Characteristics in a Circular Microchannel with Bifurcation Plate

Hydrothermal characteristics in circular wavy microchannels (CWMCs) with bifurcation plate have been numerically studied and compared with hydrothermal performance of sinusoidal wavy microchannels (SWMCs). Numerical study were carried out considering the Reynolds number (Re) ranging from 100 to 300. It was observed that, as the fluid flows through CWMC, it continuously absorbs heat from the channel leading to decrease in the temperature difference between the channel and the fluid. Hence, heat dissipation along the channel length decreases. To augment the heat dissipation along the fluid flow direction in CWMC, bifurcation plate (BFP) is introduced in the middle of the channel. CWMC with bifurcation plate has shown higher Nusselt number (Nu) with pressure drop penalty. The parametric study on bifurcation plate length was also carried out to minimize the pressure drop penalty and to achieve higher Nu. It is identified that CWMC with bifurcation plate length of 12.5 mm gives higher Nu with pressure drop penalty. Nu is further enhanced by providing slots on bifurcation plate. It is concluded that CWMC with BFP(10 mm) having slots gives the highest Nu than any other designs with pressure drop penalty.

Numerical investigation of turbulent flow and heat transfer of nanofluid inside a wavy microchannel with different wavelengths

In the present study, turbulent flow and heat transfer inside a three-dimensional wavy microchannel with different wavelengths have been numerically simulated. The main purpose of this study is to investigate the effects of changing the wavelength of the sinusoidal microchannel and CuO nanoparticle concentration on flow and heat transfer properties. For this reason, flow is simulated at Reynolds numbers of 3000, 4500, 6000, and 7500 with volume fractions of 0, 1.5, and 3% in three different geometries and the effects of each parameter have been investigated. Validation of the results showed there is an excellent agreement between the presented results with the previous studies. The average Nusselt number, pressure loss ratio, performance evaluation criterion, and local Nusselt number have been presented. Moreover, the distribution of the static temperature contour has been presented. In the flow with lower Reynolds numbers, the Nusselt number is not changed significantly; however, in flow with Reynolds number of 7500, the Nusselt number is increased. The performance evaluation criterion has the highest value in nanofluid flow with the volume fraction of 3%, indicating the effects of heat transfer with pressure drop caused by nanoparticles, and from engineering and economic perspectives, using nanoparticles in the wavy microchannel is recommended.

Transport Phenomenon of Simultaneously Developing Flow and Heat Transfer in Twisted Sinusoidal Wavy Microchannel under Pulsating Inlet Flow Condition

The transport phenomena in microchannel are significant in designing MEMS devices. The current study investigates numerically the simultaneously developing unsteady laminar flow and heat transfer inside a twisted sinusoidal wavy microchannel. At the inlet sinusoidal varying velocity component is applied. Varying pulsating amplitude and frequency represented by the Strouhal number was studied for Reynolds numbers ranging from 1 to 100. The governing equations are solved with a finite volume based numerical method. In comparison with steady flow, it was found that imposed sinusoidal velocity at the inlet can provide improved heat transfer performance at different amplitudes and frequencies while keeping the pressure drop within acceptable limits.

Convective mass and heat transfer enhancement of nanofluid streams in bifurcating microchannels

Significantly improved mixing and heat transfer between two nanofluid streams in a Y-shaped sinusoidal microchannel have been achieved via geometric modifications and changes in pulsatile flow conditions. As a result a new mass-and-heat transfer correlation has been obtained as well. The geometry modification was done in two distinct parts. First, the phase shift (ϕ) between the wavy walls of the Y-channel was varied for three different shift values 0°,90°,180°. Once the shift that yielded the highest degree of mixing was determined, the included angle (α) between the input streams was varied 30°,45°,60°. The numerical results show that α=60° and ϕ=90° yield best results. The inlet streams are pulsatile with a velocity of the form V+δVsinωt+Φ where V,δV,ω,Φ are the average velocity, pulse amplitude, pulse frequency and phase shift respectively. Flow variations have been implemented via different phase shifts 45°,90°,135°,180°, different phase amplitudes and different phase frequencies. For the sake of comparison and ease of plotting, non-dimensional parameters have been used. The frequency has been captured by the non-dimensional Strouhal number (St) and the amplitude by the amplitude ratio (δV/V). The average degree of mixing (ζ), which is observed to undergo spatial variations along the exit channel as well as temporal fluctuations over one pulsation cycle is shown to be most sensitive to the amplitude and frequency of pulsations. For a fixed amplitude, the average degree of mixing increases with elevated Strouhal numbers. It reaches a peak at a particular St value and then decreases with further increase in St. The St where the degree of mixing peaks depends on the amplitude of pulsations. For δV/V⩾5, the degree of mixing peaks at St≈0.5. For δV/V⩽5, the degree of mixing peaks at St≈2. Unlike mixing, the heat transfer rate, characterized by the non-dimensional Nusselt number (Nu) peaks at higher frequency values for all δV/V ratios. To generate higher amplitudes in the pulsating flow, a larger pumping power would be required. Hence, to minimize energy cost, low amplitude and high frequency pulsations are most suitable for optimal mixing and heat transfer.Finally, a microchannel with optimized geometry and inlet flow conditions is proposed, which takes advantage of the flow instabilities created by the modified geometry and pulsating flow to yield the highest degree of mixing and heat transfer within the listed constraints. Functional dependencies have been established, based on computer experiments, between non-dimensional parameters such as St,δV/V,ζ,Nu . As a result, a correlation between mixing and heat transfer was developed which allows studying one quantity, say, the Nusset number Nu, to readily obtain the average degree of mixing ζ.

Thermo hydraulic performance analysis of twisted sinusoidal wavy microchannels

Numerical simulation of fully developed laminar fluid flow and heat transfer in a twisted sinusoidal wavy microchannel is presented. Twisted channel is a sinusoidal rectangular channel with progressive rotation of its cross sectional geometry in stream wise direction. 3-D, unsteady, incompressible, laminar flow model with constant wall temperature and heat flux boundary conditions are simulated using SIMPLE algorithm based finite volume method. Computational procedure has been validated using available experimental data. Extensive computations have been performed to study the thermo-hydraulic performance of twisted wavy microchannels with various amplitude to wavelength ratios and twist ratios for 300 ≤ Re ≤ 700. Results show that the twisted wavy microchannels can substantially enhance heat transfer performance with minimal pressure drop for low Re number regime compared to sinusoidal microchannels. Twisted channels of higher aspect ratio and lower waviness produced heat transfer enhancement of around 30% compared to sinusoidal wavy microchannels.

Sinusoidal Microchannel with Descending Curves for Varicose Veins Implantation.

Approximately 26% of adult people, mostly females, are affected by varicose veins in old age. It is a common reason for distress, loss of efficiency, and worsening living conditions. Several traditional treatment techniques (sclerotherapy and foam sclerotherapy of large veins, laser surgeries and radiofrequency ablation, vein ligation and stripping, ambulatory phlebectomy, and endoscopic vein surgery) have failed to handle this disease effectively. Herein, authors have presented an alternative varicose vein implant method—the descending sinusoidal microchannel (DSMC). DSMC was simulated by Fuzzy logic MATLAB (The MathWorks, Natick, MA, USA) and ANSYS (ANSYS 18.2, perpetual license purchased by Ibadat Education Trust, The University of Lahore, Pakistan) with real and actual conditions. After simulations of DSMC, fabrication and testing were performed. The silver DSMC was manufactured by utilizing a micromachining procedure. The length, width, and depth of the silver substrate were 51 mm, 25 mm, and 1.1 mm, respectively. The measurements of the DSMC channel in the silver wafer substrate were 0.9 mm in width and 0.9 mm in depth. The three descending curves of the DSMC were 7 mm, 6 mm, and 5 mm in height. For pressure, actual conditions were carefully taken as 1.0 kPa to 1.5 kPa for varicose veins. For velocity, actual conditions were carefully taken as 0.02 m/s to 0.07 m/s for these veins. These are real and standard values used in simulations and experiments. At Reynolds number 323, the flow rate and velocity were determined as 1001.0 (0.1 nL/s), 11.4 cm/s and 1015.3 (0.1 nL/s), 12.19 cm/s by MATLAB (The MathWorks, Natick, MA, USA) and ANSYS simulations, respectively. The flow rate and velocity were determined to be 995.3 (0.1 nL/s) and 12.2 cm/s, respectively, at the same Reynolds number (323) in the experiment. Moreover, the Dean number was also calculated to observe Dean vortices. All simulated and experimental results were in close agreement. Consequently, DSMC can be implanted in varicose veins as a new treatment to preserve excellent blood flow in human legs from the original place to avoid tissue damage and other problems.

Fluid mixing in droplet-based microfluidics with T junction and convergent-divergent sinusoidal microchannels.

To explore and utilize the advantages of droplet-based microfluidics, hydrodynamics, and mixing process within droplets traveling though the T junction channel and convergent-divergent sinusoidal microchannels are studied by numerical simulations and experiments, respectively. In the T junction channel, the mixing efficiency is significantly influenced by the twirling effect, which controls the initial distributions of the mixture during the droplet formation stage. Therefore, the internal recirculating flow can create a convection mechanism, thus improving mixing. The twirling effect is noticeably influenced by the velocityof thecontinuous phase; in the sinusoidal channel, the Dean vortices and droplet deformation are induced by centrifugal force and alternative velocity gradient, thus enhancing the mixing efficiency. The best mixing occurred when the droplet size is comparable with the channel width. Finally, we propose a unique optimized structure, which includes a T junction inlet joined to a sinusoidal channel. In this structure, the mixing of fluids in the droplets follows two routes: One is the twirling effect and symmetric recirculation flow in the straight channel. The other is the asymmetric recirculation and droplet deformation in the winding and variable cross-section. Among the three structures, the optimized structure has the best mixing efficiency at the shortest mixing time (0.25 ms). The combination of the twirling effect, variable cross-section effect, and Dean vortices greatly intensifies the chaotic flow. This study provides the insight of the mixing process and may benefit the design and operations of droplet-based microfluidics.

Splitting and separation of colloidal streams in sinusoidal microchannels.

The control of the distribution of colloidal particles in microfluidic flows plays an important role in biomedical and industrial applications. A particular challenge is to induce cross-streamline migration in laminar flows, enabling the separation of colloidal particles according to their size, shape or elasticity. Here we show that viscoelastic fluids can mediate cross-streamline migration of deformable spherical and cylindrical colloidal particles in sinusoidal microchannels at low Reynolds numbers. For colloidal streams focused into the center of the channel entrance this leads to a symmetric stream-splitting and separation into four substreams. The degree of stream splitting and separation can be controlled via the flow rates, viscoelasticity of the focusing fluid, and the spatial microchannel modulation with an upper limit when reaching the microchannel walls. We demonstrate that this effect can be used to separate flexible particles of different size and shape. This methodology of cross-stream migration has thus great potential for the passive separation of colloids and cells in microfluidic channels.

Simulation, Fabrication and Analysis of Silver Based Ascending Sinusoidal Microchannel (ASMC) for Implant of Varicose Veins.

Bioengineered veins can benefit humans needing bypass surgery, dialysis, and now, in the treatment of varicose veins. The implant of this vein in varicose veins has significant advantages over the conventional treatment methods. Deep vein thrombosis (DVT), vein patch repair, pulmonary embolus, and tissue-damaging problems can be solved with this implant. Here, the authors have proposed biomedical microdevices as an alternative for varicose veins. MATLAB and ANSYS Fluent have been used for simulations of blood flow for bioengineered veins. The silver based microchannel has been fabricated by using a micromachining process. The dimensions of the silver substrates are 51 mm, 25 mm, and 1.1 mm, in length, width, and depth respectively. The dimensions of microchannels grooved in the substrates are 0.9 mm in width and depth. The boundary conditions for pressure and velocity were considered, from 1.0 kPa to 1.50 kPa, and 0.02 m/s to 0.07 m/s, respectively. These are the actual values of pressure and velocity in varicose veins. The flow rate of 5.843 (0.1 nL/s) and velocity of 5.843 cm/s were determined at Reynolds number 164.88 in experimental testing. The graphs and results from simulations and experiments are in close agreement. These microchannels can be inserted into varicose veins as a replacement to maintain the excellent blood flow in human legs.

Numerical investigation of flow and heat transfer characteristics in smooth, sinusoidal and zigzag-shaped microchannel with and without nanofluid

Flow and heat transfer characteristics in smooth, sinusoidal and zigzag-shaped microchannel with and without nanofluid have been investigated by finite volume method. Effects of amplitude and wave length of sinusoidal and zigzag-shaped microchannel, volume of fraction and Reynolds number on heat transfer, performance evaluation criterion were evaluated. The results show that by increasing volume fraction of Copper oxide nanoparticle, Nusselt numbers are increased. Obtained results show that if only the increase in heat transfer is considered, using sinusoidal microchannels without nanoparticles is more effective method than using of nanoparticles in smooth microchannels. By analyzing the effect of wavelength and amplitude on changes of Nusselt number, it can be found that by decreasing sinusoidal and zigzag-shaped microchannel wavelengths, Nusselt number will increase. Also, we concluded that for selection of the best microchannel, the zigzag shaped one is a more appropriate one as compared to the sinusoidal microchannel.