Effects Of Different Flow Parameters Research Articles

Latest advancements in fluid flow and heat transfer: A review studyLatest advancements in fluid flow and heat transfer: A review study

The present paper aims to provide a varied and wide range of recent advancement in fluid flow and heat transfer in different flow geometries considering the effects of different flow parameters. Several parameters like “magnetic field (applied as well as induced), porosity of the surface as well as medium, heat source/sink, radiation, absorption, free/forced convection, chemical reactions etc.” have their impact on the flow. These fluid flow problems have their applications in many engineering as well as astrophysical and geophysical problems of interests. Present study may provide the readers a brief idea about the fluid flow and heat transfer problems.

Numerical Simulation and Experimental Research on the Quenching Process of 1045 Steel Based on Thermo–Fluid–Solid Coupling Model

In the numerical simulation research on quenching, the heat transfer coefficient is an important input parameter. However, owing to its complexity and various influencing factors, the measured results are not universal and will significantly increase the simulation complexity and error. This article proposes a new numerical simulation method for quenching processes by extending the simulation domain and introducing the coupled heat exchange between the liquid quenching medium and workpiece, replacing the role of the heat transfer coefficient in the numerical simulation. The method is validated through experimental studies on 1045 steel rod quenched in water, with the maximum relative errors of the simulation results compared to the experimental results being 3.6%, 9%, and 5.1% for hardness, cooling curve, and residual stress, respectively. Furthermore, the article investigates the effect of different flow parameters of quenching media on the quenching effect. Under the studied conditions, the 1045 steel rod has the lowest risk of cracking and the highest hardness value when quenched in water at 50 °C. The proposed method improves the universality and convenience of numerical simulation for the quenching process and can be used to guide the formulation of quenching process parameters when the heat transfer coefficient is unknown.

Numerical Analysis on MHD mixed convection flow of Al_2O_3/H_2O (Aluminum-Water) Nanofluids in a Vertical Square Duct

In this work, we have considered steady laminar magnetohydrodynamics (MHD) mixed convection flow of an electrically conducting fluid in presence of nanoparticles while water as the base fluid in a vertical square duct. The walls of the duct are thermally insulated. In the energy equation, the effect of viscous dissipation and Joule heat is also considered. In this case, the walls of the duct are kept at a constant temperature. By using dimensionless quantities the governing equations of momentum, induction, and energy are first transformed into dimensionless equations. The velocity, temperature, and induced magnetic field profiles are plotted to analyze the effect of different flow parameters. It is found that the nanofluid motion expedite with the increase of the value of the parameters magnetic Reynolds number and Prandtl number. There are some important industrial applications and cooling shows in the industry of the current research. This study observed its importance with the view to increasing the heat transfer efficiency practical application relevant to industry and engineering issues. The issues discussed in this study have not been included in the earlier investigation for steady nanofluid flow due to a square duct. Numerical results are matched with an earlier published work and an excellent agreement between two are observed.

A priori assessment of nonlocal data-driven wall modeling in large eddy simulation

In the present study, a priori assessment is performed on the ability of the convolutional neural network (CNN) for wall-modeling in large eddy simulation. The data used for the training process are provided by the direct numerical simulation (DNS) of the turbulent channel flow. Initially, a study is carried out on the input choices of CNN, and the effect of different flow parameters on establishing a wall model is investigated. Then, the influence of the wall-normal distance on the established data-driven wall model is studied by choosing the CNN input data from two regions of the inner layer (y+>10,y/δ<0.1) and the logarithmic layer. The performance of the obtained CNN wall models based on the inputs from the two regions is further investigated by feeding the network with the data outside the training range. In the next step, the models are tested under various conditions, including a different grid size and a higher Reynolds number. The results show that the models using the inner layer (excluding y+≤10) data as the CNN input have better accuracy in establishing a wall model compared to the models based on the input data in the logarithmic layer, especially when implemented outside the training range. After optimizing the hyperparameters of CNN, a high correlation coefficient of 0.9324 is achieved between the wall shear stress calculated using the filtered DNS data and predicted by the best CNN wall model, which is trained using the data in the inner layer, excluding y+≤10. The performance of the CNN wall model is also compared with the existing wall-stress models, and it is shown that the CNN wall model has better accuracy in establishing a wall model. Additionally, the CNN wall model is shown to have good performance when applied to a different grid size or a higher Reynolds number.

Study on Flow Behavior in Terminal Bronchus of Human Lung for Porous Medium

Flow simulation along human lung channel is one of the interests of investigation in fluid dynamics. We have studied flow phenomena of 11th generation of human lung as porous medium. The governing equations of porous medium have been solved numerically using finite difference scheme. The effect of different flow parameters are illustrated graphically. It is observed that the flow rate increases for increasing the value of pressure gradient, the porosity effect, effective viscosity and the dimensionless parameter . The numerical experiment for non-porous medium is also studied. It is found that the flow rate increases in porous medium compared with non-porous medium. GANIT J. Bangladesh Math. Soc. 42.1 (2022) 069- 080

An experimental study of displacement flows in stationary and moving annuli for reverse circulation cementing applications

We present an experimental study of buoyant displacement flows in vertical narrow centric/eccentric annular configurations, representing the oilfield primary cementing process, from a fluid mechanics perspective. In this study, we consider the reverse circulation cementing case, i.e. the case in which the cementing fluids are pumped down from the surface into the annulus and the in-situ fluids are taken through the casing or tubing. The fluid proxies used to represent the industrial fluids are miscible, with different rheological behaviours, i.e. salt-water (Newtonian), Xanthan (shear-thinning) and Carbopol (viscoplastic) solutions, and they have various density contrasts. Our dimensional analysis and systematic simplifications allow us to describe the flow using five dimensionless numbers: m (viscosity ratio), Fr (densimetric Froude number, quantifying effects of the density difference or buoyancy), Re (Reynolds number, quantifying the effects of the imposed flow rate), e (eccentricity) and f (reciprocation frequency). We examine the effects of the aforementioned parameters in stationary and moving annuli, wherein we change the frequency of the inner pipe reciprocation motion, over a fixed amplitude. Using mainly high-speed camera imaging techniques, we analyse displacement flow patterns and mixing between the fluids. We show that the density-stable or density-unstable configurations, the non-Newtonian effects, and the annulus eccentricity exert a significant impact on the displacement flow features, which we explain through a detailed comparison between Newtonian and non-Newtonian displacements. In addition, we demonstrate that an interplay between the yield stress and the annulus motion can remarkably change the displacement flow behaviour, particularly the wall residual layer thicknesses of the displaced fluid. Finally, we quantify the effects of different flow parameters on the leading front velocity, representing the displacement efficiency in the reverse circulation cementing.

Analysis of Hydro Magnetic Flow of Visco Elastic Fluid in a Vertical Channel

In the present paper we have Analysis of hydro magnetic flow of visco elastic fluid. Hydro magnetic visco elastic fluid flow between two horizontal infinite parallel porous plates with time varying sinusoidal pressure gradient and magnetic field has been discussed in the present study. The visco elasticity in an effective approach to modeling the dissipative mechanism. Some interesting observations are low-frequency oscillating pressure gradient Prevents back flow, significant reduction in skin frictions is observed by embedding the channel in porous medium and magnetic field and elasticity decelerate the fluid flow and also in this paper a Theoretical Analysis is carried out of study the visco elastic effects on hydro magnetic heat & mass transfer in a vertical channel. The two vertical plates are in porous medium and non-uniform wall temperatures. A magnetic field of uniform strength is applied in the direction perpendicular to the plates. The visco elastic fluid flow is characterized by second order fluid. The effects of different flow parameters on skin friction are analyzed and illustrated graphically.

Wind tunnel tests on railway vehicles in the presence of windbreaks: Influence of flow and geometric parameters on aerodynamic coefficients

Crosswind stability is one of the most studied topics in the field of train aerodynamics. The interaction between a train and strong crosswinds can lead to the train overturning. One way to reduce the train overturning risk is to equip the railway line with windbreak barriers. In this work, the results obtained during wind tunnel tests on an ETR1000 high-speed train in the presence of different types of windbreaks are shown. The goal is to underline the effects of different flow parameters and geometric parameters of the infrastructure's models on the train's aerodynamic coefficients. Comparing the different test results made it possible to provide indications on which parameters are important to avoid experimental errors and reproduce as much as possible the real full-scale phenomena. Particular attention shall be paid to the dimensions of the splitter plate because a limited upwind width can lead to underestimation of aerodynamic coefficients by more than 30%. The length of the barriers in front of the train is fundamental and too short length can lead to coefficients overestimation of about 25%. Finally, coefficients measured with only the upwind windbreak row are lower (up to 50%) than those measured with a two rows configuration.

Thermal diffusion effect on unsteady MHD free convective flow past an impulsively started but temporarily accelerated semi‐infinite vertical plate with parabolic ramped conditions

AbstractThe purpose of the present study is to analyze the problem of a free convective MHD flow of incompressible, electrically conducting, and viscous fluid past an impulsively started semi‐infinite moving vertical plate. The fluid is considered to be non‐gray and optically thick. The parabolic ramped temperature of the plate and thermodiffusion effect are also taken into account. A magnetic field having uniform strength is applied in the transverse direction to the fluid velocity. Solutions of dimensionless governing partial differential equations are attained on the adoption of the closed‐form Laplace transformation technique. Effects of different flow parameters on the velocity field, temperature field, concentration field, Nusselt number, skin friction, and Sherwood Number are discussed graphically. It is noticed that fluid concentration, temperature, and velocity decline considerably for ascending values of Prandtl Number. Increasing Ramped parameter hikes the Nusselt number and Sherwood Number but declines skin friction.

Convective heat and mass transfer of chemically reacting fluids with activation energy with radiation and heat generation

TThis study is to investigate the effect of the chemical process by activation energy on heat transference and mass transference of a fluid by heat generation parameter (Hg) and radiation parameter (Rd). Attention has been given to the changes caused on the temperature by the flow in rotating frame by the heat generation parameter, Biot number, and radiation param-eter. The variation of velocity and concentration of fluid, which is chemically reacting, by the influence of the rotational parameter (β) has been incorporated. A numerical solution of the system through resulting equations has been undertaken. Effects of different flow parameters are presented by graphs and tables. Results show that activation energy increases when there is an increase in the concentration of the chemical species and that velocity decrease by the increase in porosity. With the rise of Prandtl number the temperature of the chemical sys-tem decreases. A numerical discussion on skin friction coefficients, Sherwood and Nusselt numbers has been done.

Magnetohydrodynamic oscillatory flow of a physiological fluid in an irregular channel

The impact of heat source on magnetohydrodynamic oscillatory flow of a chemically reacting viscoelastic fluid in an asymmetric wavy channel is analysed. The governing flow equations are transformed into ODEs by utilizing proper non-dimensional variables. The subsequent ordinary differential equations are solved analytically. The effects of different flow parameters on the fluid flow, thermal and species distributions as well as rate of heat and mass transfer coefficients are examined graphically. It is pointed out that the velocity of fluid is parabolic with extreme value along the channel centreline and minimum at the walls. The magnitude of fluid velocity increases with an increase in porous parameter and high heat transport of a system is due to the presence of oscillatory flow.

Cattaneo–Christov double-diffusion model for viscoelastic nanofluid with activation energy and nonlinear thermal radiation

PurposeThe purpose of this paper is to explore the novel aspects of activation energy in the nonlinearly convective flow of Walter-B nanofluid in view of Cattaneo–Christov double-diffusion model over a permeable stretched sheet. Features of nonlinear thermal radiation, dual stratification, non-uniform heat generation/absorption, MHD and binary chemical reaction are also evaluated for present flow problem. Walter-B nanomaterial model is employed to describe the significant slip mechanism of Brownian and thermophoresis diffusions. Generalized Fourier’s and Fick’s laws are examined through Cattaneo–Christov double-diffusion model. Modified Arrhenius formula for activation energy is also implemented.Design/methodology/approachSeveral techniques are employed for solving nonlinear differential equations. The authors have used a homotopy technique (HAM) for our nonlinear problem to get convergent solutions. The homotopy analysis method (HAM) is a semi-analytical technique to solve nonlinear coupled ordinary/partial differential equations. The capability of the HAM to naturally display convergence of the series solution is unusual in analytical and semi-analytic approaches to nonlinear partial differential equations. This analytical method has the following great advantages over other techniques:It provides a series solution without depending upon small/large physical parameters and applicable for not only weakly but also strongly nonlinear problems.It guarantees the convergence of series solutions for nonlinear problems.It provides us a great choice to select the base function of the required solution and the corresponding auxiliary linear operator of the homotopy.Brief mathematical description of HAM technique (Liao, 2012; Mabood et al., 2016) is as follows. For a general nonlinear equation:(1)N[u(x)]=0,where N denotes a nonlinear operator, x the independent variables and u(x) is an unknown function, respectively. By means of generalizing the traditional homotopy method, Liao (1992) creates the so-called zero-order deformation equation:(2)(1−q)L[uˆ(x;q)−uo(x)]=qhH(x)N[uˆ(x;q)],here q∈[0, 1] is the embedding parameter, H(x) ≠ 0 is an auxiliary function, h(≠ 0) is a nonzero parameter, L is an auxiliary linear operator, uo(x) is an initial guess of u(x) and is an unknown function, respectively. It is significant that one has great freedom to choose auxiliary things in HAM. Noticeably, when q=0 and q=1, following holds:(3)uˆ(x;0)=uo(x)anduˆ(x;1)=u(x),Expanding in Taylor series with respect to (q), we have:(4)uˆ(x;q)=uo(x)+∑m=1∞um(x)qm,whereum(x)=1m!∂muˆ(x;q)∂qm|q=0.If the initial guess, the auxiliary linear operator, the auxiliary h and the auxiliary function are selected properly, then the series (4) converges at q=1, then we have:(5)u(x)=uo(x)+∑m=1+∞um(x).By defining a vector and differentiating Equation (2) m-times with respect to (q) and then setting q=0, we obtain the mth-order deformation equation:(6)L[uˆm(x)−χmum−1(x)]=hH(x)Rm[u→m−1],where:(7)Rm[u→m−1]=1(m−1)!∂m−1N[u(x;q)]∂qm−1|q=0andχm=|0m⩽11m>1.Applying L−1 on both sides of Equation (6), we get:(8)um(x)=χmum−1(x)+hL−1[H(x)Rm[u→m−1]].In this way, we obtain um for m ⩾ 1, at mth-order, we have:(9)u(x)=∑m=1Mum(x).FindingsIt is evident from obtained results that the nanoparticle concentration field is directly proportional to the chemical reaction with activation energy. Additionally, both temperature and concentration distributions are declining functions of thermal and solutal stratification parameters (P1) and (P2), respectively. Moreover, temperature Θ(Ω1) enhances for greater values of Brownian motion parameter (Nb), non-uniform heat source/sink parameter (B1) and thermophoresis factor (Nt). Reverse behavior of concentration ϒ(Ω1) field is remarked in view of (Nb) and (Nt). Graphs and tables are also constructed to analyze the effect of different flow parameters on skin friction coefficient, local Nusselt number, Sherwood numbers, velocity, temperature and concentration fields.Originality/valueThe novelty of the present problem is to inspect the Arrhenius activation energy phenomena for viscoelastic Walter-B nanofluid model with additional features of nonlinear thermal radiation, non-uniform heat generation/absorption, nonlinear mixed convection, thermal and solutal stratification. The novel aspect of binary chemical reaction is analyzed to characterize the impact of activation energy in the presence of Cattaneo–Christov double-diffusion model. The mathematical model of Buongiorno is employed to incorporate Brownian motion and thermophoresis effects due to nanoparticles.

Analysis of MHD and heat transfer effects with variable viscosity through ductus efferentes

A novel theoretical model for unsteady, non-isothermal flow with temperature variant viscosity for the Newtonian fluid in the presence of transverse magnetic field is studied in the ductus efferentes of human male reproductive tract. Importance of cilia for the fluid transport through ductus efferente is elaborated in this study. To investigate the flow, we considered a channel and constant temperature difference is imposed between the wall of channel. A mathematical model is developed and analytical solution is achieved with the help of Adomian decomposition method (ADM) for MHD heat and fluid flow with temperature dependent viscosity. Flow is modeled by considering assumptions that Reynolds number is small, so that inertial forces are insignificant and wavelength to diameter ratio is maximum, so that pressure can be assumed uniform in the channel. Solutions are presented for the exponential dependent viscosity on temperature. Effect of different flow parameters on the axial and transverse component of velocity are analyzed graphically. Pumping characteristic due to ciliary beat from one row of cilia to another are investigated. Lastly variation of different flow parameters on the trapped bolus and pressure are examined graphically.

MHD and heat transfer analyses of a fluid flow through scraped surface heat exchanger by analytical solver

Scraped surface heat exchangers (SSHEs) diversely used in various industries for different settings when continuous processing of fluid and related material is required. In this work, heat transfer for steady incompressible flow of a Newtonian fluid in the presence of high magnetic field with temperature variant viscosity in a small gap of SSHE is studied for a fixed temperature difference narrow gaps between rotor and stator. The fluidic system is modeled mathematically in terms of PDEs for non-isothermal megnetohydrodynamic (MHD) flow with temperature dependent viscosity for linear blade shape. The solution of modeled PDEs are obtained analytically by exploiting the strength of Adomian decomposition method (ADM). The effects of different flow parameters of the systems are studied and their results are presented with analytical expressions and graphical illustrations.

Nonlinear convective stratified flow of Maxwell nanofluid with activation energy

The aim of present article is to explore the novel aspects of activation energy in nonlinearly convective flow of Maxwell nanofluid driven by nonlinearly stretched inclined cylinder. Generalized forms of Fourier's and Fick's law are utilized through Cattaneo-Christov double diffusion scheme. Maxwell nanomaterial model is used to describe the significant slip mechanism namely known as Brownian and thermophoresis diffusions. Features of double stratification, non-uniform heat generation/absorption, binary chemical reaction and activation energy are considered for present flow problem. Modified Arrhenius formula for activation energy is implemented. The resulting nonlinear system is cracked for series solutions via homotopy technique. Effects of different flow parameters on temperature, nanoparticle volume concentration and velocity fields are examined through graphs and tables. Numerical computations are performed for local Nusselt and Sherwood numbers. Our analysis reveals that nanoparticle concentration is directly proportional to the chemical reaction with activation energy. Moreover stratification variables diminish the temperature and concentration. It is also noticed that higher estimation of Deborah number declines the velocity profile of Maxwell fluid. Numerical outcomes are compared with previous published results and found to be in good agreement for limiting cases of the evolving parameters.

Characterization of flow mixing and structural topology in supersonic planar mixing layer

The investigations on mixing process and structural topology properties of supersonic planar mixing layer with different inflow conditions are conducted by employing direct numerical simulation. First, the present high-order accuracy numerical methods are validated by comparing the simulation results with the data gained from previous well characterized experimental and numerical cases. Then the high-resolved three-dimensional numerical visualizations of supersonic mixing layer are presented by utilizing Q-criterion. The visualization results show the full development and evolution process of mixing layer, including the shear action, the transition process populated sequentially by Λ-vortices, hairpin vortices and braid structures and the establishment of self-similar turbulence. The effects of density ratio, velocity ratio and convective Mach number between the two parallel streams on mixing layer growth rate are evaluated by examining the indexes including velocity thickness and momentum thickness represented the mixing process. The results indicate that for the only variation of density ratio, the velocity thickness growth rates do not significantly vary, while the momentum thickness becomes larger when the upper and lower streams possess the same density. With the increase of only velocity ratio, the mixing layer becomes more stable and the velocity and momentum thickness are both drastically depressed in the whole flow field. As only convective Mach number increases, the mixing layer growth is inhibited in the near field through the transition delay of the flow, while in the far field, the growth rates are nearly the same for different convective Mach numbers. The spatial correlation analysis of structural topology indicates that the effects of each of the three main flow parameters on vortex topology lead to different mean structure sizes and shapes. The present research is useful for evaluating the effects of different flow parameters on mixing properties, which is important for the future scramjet combustor design and evaluation in engineering.

Numerical investigation on the effect of different parameters in enhancing heat transfer performance of photovoltaic thermal systems

Abstract Photovoltaic thermal (PV/T) collectors that supply both electricity and heat are growingly becoming popular in household and other applications. However, efficient heat removal from backside of PV module is still a challenge that hampers its electrical as well as thermal performance. In the present research, an absorber-plate less thermal collector has been introduced and mathematical model of such a PV/T system has been developed, which is employed in COMSOL Multiphysics® software to simulate the heat transfer phenomenon in the system. Effect of different flow parameters on heat transfer and PV/T performance is thus studied numerically in the developed simulation model. Also, the effect of irradiation level and depth of the flow channel has been examined on the thermal as well as electrical performance of the module. Results reveal that PV/T electrical and thermal efficiency increase with both of Reynolds and Prandtl number. Heat transfer rate is observed to increase as high as 25.5% with increasing Reynolds number. A maximum reduction in cell temperature of 10.2 °C is obtained by increasing the channel depth. Elimination of absorber plate from thermal collector simplified the design reducing its weight and cost as well.

Unsteady flow and heat transfer past a permeable stretching/shrinking sheet in a nanofluid: A revised model with stability and regression analyses

This article investigates the unsteady flow and heat transfer in a nanofluid over a stretching/shrinking sheet with injection/suction effects to overcome the deficiency found in the previous model that was to control the nanoparticles fraction actively. Besides, this study controls the nanoparticles volume fraction on the boundary passively rather than actively in order to make the model physically more realistic with zero flux at the surface. This approach makes the Buongiorno's nanofluid model more effective for the plate problems in reality. The governing partial differential equations are transformed into ordinary differential equations via the similarity transformation and are then solved numerically using the bvp4c function. Effects of different flow parameters on the velocity profile, the temperature distribution, the skin friction coefficient and the local Nusselt number are deliberated in detail. Dual solutions are observed for the stretching/shrinking sheet and suction/injection parameter in some certain range. Stability analysis is conceived to check the reliability and stability of the solutions. The local Nusselt number is estimated through multiple linear and quadratic regressions. A comparison is made to validate the obtained results. Results indicate that the first solution is stable and physically realizable as compared to the second solution either fluid flow is under suction or injection effect. The Brownian motion parameter is not significant, and the local Nusselt number is almost independent of the Brownian motion parameter, but it depicts decreasing behavior for the Schmidt number and the thermophoresis parameter for suction and opposite behavior for the injection case. The rise in the suction parameter causes the streamlines to get closer to each other while for the impermeable case, the oncoming flow is the same as for the stagnation point flow.

Investigation of Nanoparticle as a Drug Carrier Suspended in a Blood Flowing Through an Inclined Multiple Stenosed Artery

In the present study, a single and discrete phase model is employed to obtain analytical solutions of velocity, temperature, and stream function to describe the transport characteristics of a newtonian blood-gold, silver, or copper nanofluid flowing through an inclined multiple stenose artery, under the influence of externally applied heat. The spherical gold nanoparticles are used for discrete phase model to track the nanoparticle in the blood flow within the artery containing multiple stenosis, which is not explored so far. Apart from estimating the velocity, temperature distributions, and stream function, an explicit expression is derived for wall shear stress distribution. The effects of different flow parameters are depicted through graphs for different values of interest. The results reveal that the hemodynamics effects of stenosis reduce with an increase of particle concentration in the blood and also finding that the drug gold nanoparticles are more effective to reduce hemodynamics of stenosis when compared to the drug silver or copper nanoparticle. The normal flow of blood is observed for only 0.03 volume fraction of gold nanoparticle. We also demonstrate that cylindrical-shaped nanoparticle is more effective for drug delivery than spherical shaped as it has less wall shearing stress. The significant effect of Brownian motion is observed on gold nanoparticle in two-phase model. This study would provide valuable information for nanoparticle distribution in a vascular artery in the field of nanoparticle drug delivery.

Impact of melting heat transfer and nonlinear radiative heat flux mechanisms for the generalized Burgers fluids

The present paper deals with the analysis of melting heat and mass transfer characteristics in the stagnation point flow of an incompressible generalized Burgers fluid over a stretching sheet in the presence of non-linear radiative heat flux. A uniform magnetic field is applied normal to the flow direction. The governing equations in dimensional form are reduced to a system of dimensionless expressions by implementation of suitable similarity transformations. The resulting dimensionless problem governing the generalized Burgers is solved analytically by using the homotopy analysis method (HAM). The effects of different flow parameters like the ratio parameter, magnetic parameter, Prandtl number, melting parameter, radiation parameter, temperature ratio parameter and Schmidt number on the velocity, heat and mass transfer characteristics are computed and presented graphically. Moreover, useful discussions in detail are carried out with the help of plotted graphs and tables.