Solution Of Fluid Flow Research Articles

An analytical solution of MHD non-Newtonian fluid flow over a stretching surface with mixed convection and porous media

An analytical solution of MHD non-Newtonian fluid flow over a stretching surface with mixed convection and porous media

DUFOUR, SORET AND DISSIPATION EFFECTS ON MAGNETOHYDRODYNAMIC FLOW PAST A STRETCHING PERMEABLE SHEET WITH RADIATIVE CHEMICAL REACTION ANDHEAT SOURCE

Present investigation explores the numerical solution of Magnetohydrodynamic laminar steady gray fluid flow with heat and mass transfer past a stretching permeable sheet, incorporating several factors such as heat source, viscous and joules dissipation effects, thermal radiation, chemical reactions, Soret and Dufour effects. The governing nonlinear PDEs are simplified into ODEs with the help of similarity transformations. Momentum equation is solved analytically. Non-Dimensional temperature and concentration calculated with the help of RK- shooting method with Nachtsheim-Swigert iteration method. Key results include the calculation of heat and mass transfer rates and Co-efficient of skin friction. The effects of various parameters such as magnetic field strength, suction, radiation, chemical reactions, internal heat generation and dissipative effects on the flow characteristics and other physical parameters are thoroughly investigated, highlighting their impact on the thermal and concentration profiles in the system. This comprehensive analysis provides insights into the behaviour of the fluid flow under the specified conditions, which can be useful for applications in engineering and industrial processes.

Addressing performance improvement of a neural network model for Reynolds-averaged Navier–Stokes solutions with high wake formation

PurposeDeep-learning techniques are recently gaining a lot of importance in the field of turbulence. This study focuses on addressing the problem of data imbalance to improve the performance of an existing deep learning neural network to infer the Reynolds-averaged Navier–Stokes solution, proposed by Thuerey et al. (2020), in the cases of airfoils with high wake formation behind them. The model is based on a U-Net architecture, which calculates pressure and velocity solutions for fluid flow around an airfoil.Design/methodology/approachIn this work, we propose various methods for training the model on selectively generated data with different distributions, which would be representative of the under-performing test samples. The property we chose for selectively generating data was the fraction of negative x-velocity in the domain. We have used Grad-CAM to compare the layer activations of different models trained using the proposed methods.FindingsWe observed that using our methods, the average performance on the samples with high wake formation (i.e. flow over airfoils at high angle of attack) has improved. Using one of the proposed methods, an average performance improvement of 15.65% was observed for samples of unknown airfoils compared to a similar model trained using the original method.Originality/valueThis work demonstrates the use of imbalanced learning in the field of fluid mechanics. The performance of the model is improved by giving significance to the distribution of the training data without changes to the model architecture.

Thermal internal resistance minimisation in microchannel heat sink with perforated micro fins geometry

This study presents a 3-D numerical analysis of complex heat exchanger systems featuring innovative fin geometries. These geometries are created by modeling and placing micro fins with perforated square, circular, and rectangular designs on the heat sink. The objective of the study is to minimise thermal resistance in a hybrid heat exchanger featuring various fin architectures. The hydraulic diameter ranges from 0.036 to 0.047 mm, with fin dimensions of 0.04 mm in height and length, and 0.02 mm in width. The fins are designed with square perforations of 0.01 mm, circular perforations with a diameter of 0.015 mm, and rectangular perforations measuring 0.04, 0.012, and 0.006 mm. A high-density heat flux q″ is applied to the bottom wall, and fluid with a Reynolds number ranging from 400 to 500 is used to dissipate the heat in the cooling channel. The finite volume method and computational fluid dynamics code are employed to discretise and solve for thermal and fluid flow solutions. The impact of Reynolds number on minimised temperature and thermal resistance is analysed for void fraction ratio (VFR) of 0.25, 0.44, and 0.18.The numerical analysis reveals that the hybrid microchannel, featuring double square, circular, and rectangular perforations, demonstrates a reduction in resistance by 15 %, 21 %, and 19 %, respectively, when the coolant Reynolds number is increased by 20 %. Notably, the heat sink with square perforations exhibits the most substantial decrease in resistance, followed by circular and rectangular perforations. The numerical code is validated with what is available in the existing literature.

A thermodynamic computational model analysis of a newly designed Tri-Rotor (T-R) volume air compressor

A thermodynamic computational modelling (TCM) approach is developed to model and simulate thermodynamic processes of a newly designed rotary type air compressor named ‘tri-rotor (T-R) compressor’ using a Lattice-Boltzmann Method (LBM) based fluid flow solution, which is applied for the first time to a rotary compressor flow. With this method, which is combined with a Wall-Adapting Local Eddy-viscosity sub-grid scale stress (SGS) model (WALE), time-consuming classic fluid-domain meshing/re-meshing process is not required and a mesh deformation problem leading to numerical instability is overcome by generating a fixed Cartesian lattice. The proposed TCM approach here is expected to serve as a basis for transient simulations of rotating turbulent and highly compressible flow for accurate and more complete computational representation of an ideal, adiabatic compression process through pressure − rotational angle (P-Theta degree) and volume − rotational angle (V-Theta degree) diagrams. The designed compressor is comprised of three specifically shaped, simultaneously rotating rotors, which are well-positioned in a cylinder to draw and discharge air uninterruptedly through two-suction and two-discharge ports, respectively and achieves higher mass-flow rates with increasing rotational speed. A comparative study with different rotational speeds predicts that high isentropic efficiency ranging from 0.850 to 0.941 can be attained for the investigated rotational speed range without any compromise on mass flow rates and pressure ratios. A proof-of-concept experiment of a full-scale T-R compressor model is conducted to assess its operational feasibility and performance. It is found that the TCM approach reproduces comparable results to those obtained from the preliminary experimental studies.

More accurate solution of mixed convection radiative power law fluid flow over a stretching porous surface with presence of Forchheimer and chemical reaction

In hydraulic analysis, one of the most popular viscosity models for non-Newtonian fluids is the Power Law model. In shear-thinning and shear-thickening, the governing system of partial differential equations is transformed into a system of coupled highly non-linear ordinary differential equations. The effects of emerging parameters on velocities, temperature, and concentration as well as the engineering quantities (friction factor, Nusselt number, and Sherwood number) are presented in tables, graphs, and discussed. Most previous studies do not care about studying the effect of different parameters on stream velocity, and this is one of the advantages of our current study, which can be used by researchers in the future to make comparisons and verify the validity of the solutions. The higher accuracy of fifth-order FDM is tested by comparing it (in the Newtonian case) with previously published works and the results are in excellent agreement with these analytical and numerical works.

Effect of aircraft landing angle on hydrodynamics characteristics during wave landing

In order to study the effect of different courses on the landing performance of aircraft when landing in waves, a Computational Fluid Dynamics (CFD) method is developed to investigate the landing performance of the NACA TN 2929 A aircraft model. The solution of fluid flow is based on the Reynolds-averaged Navier-Stokes equations with the shear stress transport (SST) k−ω turbulence model, and the numerical scheme employed is the Finite Volume Method (FVM). The fifth-order Stokes wave is generated by using the velocity inlet wave-making method. In the work, the slamming load, pitch change and motion response of the aircraft landing at different wave positions are analyzed. The landing characteristics of aircraft landing parallel to the wave, perpendicular to the wave and at the yaw angle are studied. It is found that the landing characteristics of the aircraft at the 1/2 π phase are better than those at other ones, with the maximum load at the π phase. When the aircraft lands parallel to the wave, yaw displacement generated at 1/2 π phase and 3/2 π phase is equal in magnitude and opposite in direction in the initial short time. These results are important for reducing slamming loads and improving the airworthiness of the aircraft structure when landing on a wave surface.

An Analysis of the Carreau Fluid Pumping According to the Saffman Slip Condition Using an Asymmetric Direction by Peristaltic Pumps

Hall Effect of the peristalsis pump on a Carreau fluid is analyzed in the Saffman slip boundary conditions at the walls. Asymmetric channel is taken into consideration by wave’s propagation on the channel walls. Long wavelength and low Raynold number assumption an asymmetric into consideration for obtaining the fluid flow solution. The perturbation method is applied for solving the constructed mathematical model and the results are obtained for various characteristics of the fluid. Different graphical representations and comparisons have been examined to discuss various developments of fluid characteristics parameters of interest individually.

A general analytical solution for fluid flow and heat convection through arbitrary-shaped triangular ducts: A variational analysis

This paper presents an analytical solution for fluid flow and heat transfer inside arbitrarily-shaped triangular ducts for the first time. The former analytical solutions are limited to the special case of isosceles triangular ducts. The literature has no report about the analytical solution for the general case of arbitrarily-shaped triangular ducts. Due to the significant role of fluid flow through non-circular channels in industry and the large number of triangular shapes, a method for solving the heat transfer problem for all triangular shapes is needed. The heat transfer of a fluid flow through a channel with an arbitrary triangular cross-section for the case of constant heat flux at the walls is solved in this work for the first time, considering viscous dissipation. Here, the functionals of flow and heat transfer equations are derived, and the resulting Euler–Lagrange equations are solved using the Ritz method. The effect of the duct geometry on the velocity profile and friction coefficient is studied in detail. The effect of the Brinkman number on the temperature distribution and Nusselt number is investigated for both cooling and heating cases. The results reveal that the critical Brinkman Number distinguishes between the cooling and heating cases and represents the critical point at which the Nusselt number approaches infinity. The value of the Nusselt number decreases with the increase of the Brinkman number in both the wall cooling and heating modes. It is also found that the equilateral triangle exhibits the minimum friction coefficient and the maximum value of the Poiseuille number.

A numerical solution for fluid flow in unsaturated porous medium (soil)

We solve the two - dimensional mixed form Kirchhoff transformed Richards equation numerically using Crank - Nicolson scheme. This procedure has been integrated using cylindrical coordinates in an axially symmetric diffusion of flow in a homogeneous, isotropic porous medium.The soil has uniform hydraulic conductivity and no source or sink.The framework is cylindrical with a finite difference structured mesh.This procedure is particularly targeted at infiltration into dry soil, drainage, perched water table and flow through homogeneous materials. However, it is also applicable to any process involving flow through porous medium.The scheme we used is more accurate, comprehensive and is computationally efficient. It may provide a suitable basis for the implementation in large scale.

Analytical solution for unsteady Walters-B fluid flow by a deforming surface with acceleration using OHAM based package BVPh2.0

Current study aims at simulating fluid flow due to a deformable heated surface in an otherwise static viscoelastic fluid obeying Walters-B model. Velocity of the surface is supposed to grow as time from its initiation of motion progress. Simulations in this work are based on the assumption of quadratic surface temperature distribution. Temperature rise attributed to the frictional heating effect is accounted for in the analysis. By choosing appropriate base functions, homotopy solutions are developed for reasonably large values of material fluid parameter. Reliability of the analytical results is established by computing averaged squared residual of the system. The contributions of the surface acceleration and elasticity on the boundary layer formation are enlightened through the plots of velocity components and temperature. Skin friction measuring the stress experienced by the surface is evaluated and examined under different controlling parameters. The paper also presents a numerical solution using NDSolve of MATHEMATICA in a special case of steady flow, and such solution agrees very well with the corresponding homotopy solution.

Thermal and optical investigations of various transparent wall configurations and building integrated photovoltaic for energy savings in buildings

The growing global attention on energy consumption in buildings, along with the harmful effects of carbon dioxide emissions on climate change, has recently heightened efforts on sustainability and energy savings in buildings. As a result, the search for high thermal resistance walls, as well as the development of integrated photovoltaic technology with front glass walls to save energy in buildings, is an important and promising topic. The current study investigates and compares the energy-saving capabilities of four building transparent wall configurations: basic glass, facade, basic glass integrated with photovoltaics, and facade integrated with photovoltaics at different ambient temperatures, wind speeds, and solar radiation. The study also introduces a comprehensive three-dimensional heat transfer and electrical model that combines a Steady-State Thermal solution with the ANSYS mechanical solver and a fluid flow solution with the ANSYS Fluent solver to simulate the full layers of Cadmium Telluride solar cells, transparent walls, and the air conditioning room. Each model was subjected to a full-day simulation using Egypt weather conditions in the summer season to evaluate the efficacy in terms of saving artificial lighting loads, thermal loads for air conditioning, daily electricity generation from Cadmium Telluride solar cells, and total energy savings throughout the day. According to the findings, the facade integrated with photovoltaics and basic glass integrated with photovoltaics configurations deliver about 394 Wh/m2 of electrical energy to the building daily. Furthermore, when air conditioning and lighting loads, as well as solar cell productivity, are considered, the facade, basic glass integrated with photovoltaics, and facade integrated with photovoltaics configurations save 46.9%, 31.5%, and 79.3% of total electricity consumption, respectively, when compared to the basic glass wall.

Similarity solution of fractional viscoelastic magnetohydrodynamic fluid flow over a permeable stretching sheet with suction/injection

A novel easy‐to‐use similarity technique for spatial fractional partial differential equations is introduced to solve the flow and heat transfer of fractional viscoelastic magnetohydrodynamic (MHD) fluid over a permeable stretching sheet. The proposed method represents a new technique for deriving similarity transformations, which allows the conversion of the fractional partial differential equations to fractional ordinary differential equations. Moreover, using the Grünwald–Letnikov formula, the fourth‐order Runge–Kutta method is adopted here to solve the obtained similarity equations, using the shooting method. The transformed governing equations were found to be dependent on six physical parameters, namely, fractional parameter, magnetic field parameter, generalized local Reynolds number, generalized Prandtl number, the wall suction/injection parameter, and the wall stretching exponential. The results reveal that maximums of the skin friction coefficient and local Nusselt number are obtained for fractional‐order derivative of about 0.5. Moreover, application of a magnetic field on electrically conducting fractional fluid thins the velocity boundary layer and thickens the thermal boundary layer; therefore, the skin friction coefficient increases whereas the local Nusselt number decreases. Furthermore, an increase in any parameters of the local Reynolds number, suction parameter, or the wall stretching exponential leads to thinner boundary layers and higher values of skin friction coefficient and local Nusselt number, whereas imposing injection has opposite effects. Finally, increasing the generalized Prandtl number leads to a thinner thermal boundary layer and higher local Nusselt number for the fractional viscoelastic fluid. It would be of interest to extend the proposed method to other practical problems in the same field.

A multi-resolution DFPM-PD model for efficient solution of FSI problems with structural deformation and failure

This paper presents an accurate and efficient multi-resolution model for reproductions of fluid-structure interaction (FSI) issues involving intricate fluid flow phenomena, as well as structural deformation and failure. The proposed model comprises two modules, i.e., the decoupled finite particle method (DFPM) module for the solution of fluid flow, and the peridynamics (PD) module for simulating motion, deformation, fracture, and contact of structures. By employing distinct particle spacing and time step increments for the two modules, the model achieves spatial-temporal multi-resolution discretization. To address the fluid-structure interfacial region accurately, a disguised ghost particle (DGP) coupling scheme, incorporating a common smoothing length and a tensile instability control (TIC) technique, is developed. The particle inconsistency at the fluid-structure interface is resolved through the use of ghost particles and DFPM approximation, thus enabling more precise computation of interaction forces. Furthermore, a contact model is incorporated into the PD module to reflect contact interactions between solid structures. A set of benchmarks are investigated to validate the accuracy, robustness as well as efficiency of the presented multi-resolution model, and then it is further employed to simulate structural failure due to tsunami waves, which demonstrates its capability of handling engineering FSI problems with structural failure.

Drag and uncertainty of power-law fluid flows in fractal multiparticle systems

In this study, new approaches are developed to predict the drag and assess its potential uncertainty of a non-Newtonian fluid in a multiparticle system. First, a new and simpler approximate solution of power-law fluid flow is developed using the free surface cell model. Second, the uncertainty of drag in a fractal multiparticle system is investigated by treating the heterogeneous voidage in the system as a truncated power-law fractal distribution. The results demonstrate that the developed simpler approximate solution works well compared to the analytical solutions and experimental data. Incorporating truncated power-law fractal voidage can better capture the experimental data. The voidage heterogeneity increases the drag of the power-law fluid moving through the multiparticle system. Strong shear-thinning effects of power-law fluids and high mean voidage diminish the effect of voidage heterogeneity. The flow drag of power-law fluid in the heterogeneous multiparticle system decreases with increasing fractal dimension.

Effect of fracture geometry, topology and connectivity on energy recovery from enhanced geothermal systems

A combination of hydraulic fracturing and horizontal wells is now being used to tap geothermal energy from naturally fractured reservoirs. Fully grid-based numerical models are currently used to simulate heat recovery from enhanced geothermal systems (EGS). Such models require a fine unstructured mesh and are computationally expensive. In this paper we present a computationally efficient model that allows us to accurately simulate fracture propagation, fluid flow, and heat transfer in networks of natural fractures that may be created in naturally fractured geothermal reservoirs.The integrated simulator is developed by combining the displacement discontinuity method (DDM) for fracture propagation in naturally fractured reservoirs with a general Green's function solution for fluid and heat flow from the matrix to the fracture. This eliminates the need to discretize the matrix domain resulting in a very computationally efficient solution. A discrete fracture network (DFN) approach is used to represent the pre-existing natural fractures.The model is first validated against an analytical solution for fluid flow and heat transfer in a rock matrix with a single fracture. The computation time with and without discretizing the rock matrix shows a 100-fold reduction in computation cost with very little loss in accuracy. Parametric studies are conducted to investigate the effect of the distribution of natural fracture density, length, and orientation. The results show that the efficiency of tapping geothermal energy is impacted by geometrical and topological complexities of the fracture network and in particular the connectivity of backbone fractures. It is, therefore, important to optimize (not maximize) the connectivity and complexity of the backbone fracture network. The computationally efficient model presented here provides a practical tool for optimizing operational parameters for efficient geothermal production.

An analytical solution for fluid flow against valve closure in a long pipeline

An analytical solution for fluid flow against valve closure in a long pipeline

Non-similar solution for a power-law fluid flow over a moving wedge

Heat transport (HT) efficiency in boundary layer flow (BLF) across wedges is critical for many industrial processes, as well as aerospace and defence research. The HT analysis in a power-law fluid along a moving permeable wedge is described in this paper. A changeable parameter is the injection velocity at the wedge surface. The governing equations are dimensionless, and the shooting technique is used to achieve a non-similar solution. Graphs depict the impacts of various factors on the velocity and temperature contours, local Nusselt number, and skin friction coefficient. The results show that the dilatant fluid has a velocity decline near the wedge surface and achieves its maximum velocity away from the wedge surface. The findings of this study may aid in the development of better HT systems for a variety of applications.

A Fast Hybrid Pressure-Correction Algorithm for Simulating Incompressible Flows by Projection Methods

To enforce the conservation of mass principle, a pressure Poisson equation arises in the numerical solution of incompressible fluid flow using the pressure-based segregated algorithms such as projection methods. For unsteady flows, the pressure Poisson equation is solved at each time step usually in physical space using iterative solvers, and the resulting pressure gradient is then applied to make the velocity field divergence-free. It is generally accepted that this pressure-correction stage is the most time-consuming part of the flow solver and any meaningful acceleration would contribute significantly to the overall computational efficiency. The objective of the present work was to develop a fast hybrid pressure-correction algorithm for numerical simulation of incompressible flows around obstacles in the context of projection methods. The key idea is to adopt different numerical methods/discretisations in the sub-steps of projection methods. Here, a classical second-order time-marching projection method, which consists of two sub-steps, was chosen for the purposes of demonstration. In the first sub-step, the momentum equations were discretised on unstructured grids and solved by conventional numerical methods, here a meshless method. In the second sub-step (pressure-correction), the proposed algorithm adopts a double-discretisation system and combines the weighted least-squares approximation with the essence of immersed boundary methods. Such a design allowed us to develop an FFT-based solver to speed up the solution of the pressure Poisson equation for flow cases with obstacles, while keeping the implementation of the boundary conditions for the momentum equations as easy as conventional numerical methods do with unstructured grids. The numerical experiments of five test cases were performed to verify and validate the proposed hybrid algorithm and evaluate its computational performance. The results showed that the new FFT-based hybrid algorithm works and is robust, and it was significantly faster than the multigrid-based reference method. The hybrid algorithm opens an avenue for the development of next-generation high-performance parallel computational fluid dynamics solvers for incompressible flows.

THE RESONANCE EXPANSION SYSTEM FOR EMISSIONS REDUCTION OF INTERNAL COMBUSTION ENGINES

One of the main problems of today’s automotive manufacturers are emission norms that are getting much stricter. According to these high demands, car manufacturers are developing new systems to keep exhaust emissions at the lowest possible level. The resonance expansion system for emissions reduction of internal combustion engines could decrease emissions production not only in modern vehicles but also in older vehicles by additional mounting on the exhaust system. This article shows the resonance expansion system technical solution and simulations of fluid flow done in flow simulation software. The resonance expansion system is also patented, and further experiments for design improvement are planned in the near future.