Numerical Analysis Of Flow Research Articles

Unsteady MHD free convection flow of an exothermic fluid in a convectively heated vertical channel filled with porous medium

Utilizing porous media in a new mathematical model to improve convective heat transfer characteristics in a variety of applications, such as radiation nuclear disposal storing, evaporation cooling, sieving, geological extraction, crude petroleum refining, and building heating and cooling, is becoming increasingly important. This study proposed a numerical analysis of the unsteady magnetohydrodynamic free convection flow of an exothermic fluid with Newtonian heating. This discovery reveals two types of solutions: steady state and unsteady state. After transforming the governing equation from dimensional form to dimensionless form, the steady state governing equation was solved by the Homotopy Perturbation Method. However, the implicit finite difference approach is used to solve the time-dependent governing equations numerically. The impact of various emerging parameters, namely the Hartmann number, Boit number, Darcy number, Navier slip parameter, and the Frank-Kamenetskii parameter, was discussed and graphically analyzed. During the computations and analysis, it was discovered that a minor rise in the Hartman number results in the Lorentz force, which streamlines the momentum barrier layer and hence slows the fluid flow. The fluid velocity, on the other hand, rose as the porous medium, thermal Biot number, slip parameter, and temperature field increased as the viscous reactive fluid parameter and Newtonian heating increased. The skin friction and Nusselt number were also examined and reported. By comparing the finding to an existing work, a great agreement was revealed.

Numerical Investigations about Flow Resistance Values for Stirling Type Pulse Tube Cryocooler

Pulse tube cryocoolers are extensively used for space application because of simplicity and reliability in operation. Many researchers have attempted the numerical analysis of the oscillatory flow inside the cryocooler, however, the precise predictions of the exact behavior of the gas inside the cryocooler using CFD has not yet been reported. While performing the CFD analysis of cryocooler, the values of inertial and viscous resistance coefficients play vital role and highly contributes to the pressure drop taking place in porous media. The prime objective of present work is to analyze the effect of these resistance values on performance of cryocooler. A single stage Stirling type pulse tube cryocooler model from literature is employed to perform the CFD analysis and the results obtained from the analysis are validated to ensure that methodology used for analysis is correct. The resistance values mentioned in the literature are applicable for steady and unidirectional flows. The model is further modified for the values of resistances for oscillating flow at room temperature and oscillating flow at cryogenic temperature. It is observed that performance predictions for oscillating flow at cryogenic temperature resistance values yields substantially lower temperature than all other cases. As experimental validation of this model is still not reported in literature, the reliability of accurate resistance values is not confirmed. Hence, another model of single stage Stirling type pulse tube cryocooler from literature is numerically analyzed for various operating conditions and is compared with its experimental performance, and found to be in fair agreement.

Numerical analysis of electromagnetic squeezing flow through a parallel porous medium plate with impact of suction/injection

Over the years, the squeezing fluid motion between parallel plates has generated the research interest in many investigators due to its various engineering and industrial applications such as injection modeling, compression and polymer process industry. With these motivations, in the current article, the transient state electro-osmotic squeezing propulsion of viscous liquid between two parallel plates through a porous medium with the impact of radiative heat flux has been examined. The applied magnetic field inclination angle ranges from 0 to 90 degrees and moving closer together causes the plates to squeeze one another orthogonal to the plates’ surfaces. Through the suitable similarity transformations, the nonlinear partial differential equations characterizing the proposed flow model are reduced to a set of nonlinear ordinary differential equations. The numerical findings were achieved via MATLAB software. It is determined that the applied electric and magnetic field have the impact on the velocity and heat transfer of squeezing flows. Increasing the electroosmosis parameter as well as the electric field parameters have a considerable effect on temperature augmentation. The results of the current study can be used in various industrial applications such as chemical engineering, hydraulic lifts, polymer processing and power transmission.

Numerical analysis of bioconvection-MHD flow of Williamson nanofluid with gyrotactic microbes and thermal radiation: New iterative method

Abstract The aim of this study is to investigate the numerical analysis of an innovative model containing, bioconvection phenomena with a gyrotactic motile microorganism of magnetohydrodynamics Williamson nanofluids flow along with heat and mass transfer past a stretched surface. The effect of thickness variation and thermal conductivity feature is employed in the model. Bioconvection in nanofluid helps in bioscience such as in blood flow, drug delivery, micro-enzyme, biosensors, nanomedicine, for content detection, etc. For simulation procedure, the mathematical partial differential equations are converted into dimensionless systems owing to dimensionless variations such as magnetic field, power index velocity, Williamson parameter, wall thickness parameter, thermal conductivity variation, Prandtl number, thermal radiation, Brownian motion, Lewis number, Peclet number, and different concentration parameter, etc. For numerical simulation, New Iterative Technique (NIM) numerical algorithm is adopted and employed for the linear regression planned for the proposed model. For comparison purposes, the homotopy technique is employed on the flow model. Close agreement is seen between both methods revealing the accuracy and consistency of NIM numerical technique. Many features of no-scale constraints are evaluated through graphical data for a key profile of the flow model. Results show that microorganism concentration is heavy due to the magnetic effect and Hall current.

Numerical Analysis of the Condensing Steam Flow by Means of ANSYS Fluent and in-House Academic Codes With Respect to the Capacity for Thermodynamic Assessment

In this paper numerical analysis of the condensing steam flow in a converging-diverging nozzle is investigated. The ANSYS Fluent results are compared with the results of the in-house academic Computational fluid dynamics code with respect to the capacity for thermodynamic assessment. The “local” real gas equation of state is used as a mathematical complement of flow governing equations in the in-house code. In the Fluent code, the thermodynamic functions as well as the steam and water physical properties are calculated based on the IAPWS formulation with the use of the UDF. The condensation model with the Fuchs and Sutigin correction of the droplet growth equation and nucleation rate with the Kantrowitz correction is implemented in both CFD codes. The CFD results are compared with the obtained experimental data. The experiment was carried out using an in-house steam facility with a transonic steam tunnel. The investigated geometry is a converging-diverging nozzle as adopted under the International Wet Steam Experimental Project with the diverging section expansion rate of 3,000 s−1 and the total throat height of 40 mm.

Three-dimensional numerical analysis of flow and heat transfer of bi-directional stretched nanofluid film exposed to an exponential heat generation using modified Buongiorno model

The heat transfer characteristics of copper/water nanofluid flow over a bi-directional stretched film are theoretically studied. The used mathematical model accounts for nanofluid effective dynamic viscosity and thermal conductivity. The model of the current study utilizes the modified Buongiorno model to scrutinize the effect of haphazard motion, nanoparticles' thermo-migration, and effective nanofluid properties. 3D flow is driven by having the nanofluid film elongation in two directions. The thermal analysis of the problem considers the nonlinear internal heat source and Newton heating conditions. In modeling the problem, the Prandtl boundary layer approximations are employed. Moreover, the nonlinear problem set of governing equations for investigating the transport of water conveying copper nanoparticles was non-dimensionalized before being treated numerically. The current parametric study investigates the impact of governing parameters on nanoparticles velocities, temperature, and concentration distributions. The presence of copper nanoparticles leads to a higher nanofluid temperature upon heating. The temperature enhances with the nanoparticles Brownian movement and thermo-migration aspects. Furthermore, involving a heat source phenomenon augments the magnitude of the heat transfer rate. Moreover, the velocity ratio factor exhibits decreasing behavior for x-component velocity and increasing behavior for y-component velocity. In conclusion, the study results proved that for larger values of Nb and Nt the temperature is higher. In addition, it is clear from the investigations that the Lewis number and Brownian motion factor decline the nanoparticle concentration field.

Numerical analysis and two-phase modeling of water Graphene Oxide nanofluid flow in the riser condensing tubes of the solar collector heat exchanger

Graphene Oxide is one of the carbon-based-materials that has wide application range such as Water purification, Flexible rechargeable battery electrode, Solar Collectors, and Energy conversion. In this research, initially, Graphene Oxide nanoparticles were dispersed in water to make a nanofluid. The nanofluid was prepared at 0.10, 0.15, 0.20, 0.25, 0.35, and 0.45% mass fractions. After that, heat transfer and viscosity (at 10 and 100 Revolutions per minute (RPM)) of the prepared samples were calculated at 25, 30, 35, 40, 45, and 50 °C temperatures. In the Flat Plate Solar Collector (FPSC) - Riser tube, from the start point to the end of tube, the temperature decreases and thus the heat transfer and viscosity change. As the calculated range does not contain all the temperatures and mass fractions, and to lower the experimental costs, thus, Fuzzy system and Artificial Neural Network models were used to predict the whole range of data. After that, the trained models were compared to detect the error and to choose the best model with the least error. Results confirmed that Fuzzy system has lower error. This means that Fuzzy system predicts the input-target dataset as definite as obtainable.

Verified simulation of the stationary polymer fluid flows in the channel with elliptical cross-section

This work is aimed at the numerical analysis of the stationary non-isothermal flows of an incompressible viscoelastic polymer fluid in the channels with elliptical cross-sections. The description of such flows is done on the basis of the mesoscopic approach, and the resolving equations are derived. For solving them three algorithms, which use different techniques of constructing the approximate solutions, are designed: the least-squares collocation method based on the piecewise polynomial approximations, which lead to the overdetermined systems of linear algebraic equations; the finite element method, which uses weak formulations; and the non-local method without saturation, which operates with the global approximations in the elliptical coordinate system and with the matrix Sylvester equations. The proposed algorithms are verified by solving the test problem with the known analytical solution. Further we use them for the numerical analysis of the polymer fluid flows with its parameters varying in wide ranges. Comparison of the results obtained by the different algorithms shows their high performance and confirms that the solution of the considered non-linear problem exists and that it was computed accurately. The singularities of the obtained stationary solutions are analyzed. Taking them into account within the proposed algorithms enables us to increase the accuracy and the speed of simulations.

Comment on the paper “Numerical analysis for the non-Newtonian flow over stratified stretching/shrinking inclined sheet with the aligned magnetic field and nonlinear convection, Muhammad Bilal, Muzma Nazeer, Archives of Applied Mechanics, 2021, 91: 949–964”

Comment on the paper “Numerical analysis for the non-Newtonian flow over stratified stretching/shrinking inclined sheet with the aligned magnetic field and nonlinear convection, Muhammad Bilal, Muzma Nazeer, Archives of Applied Mechanics, 2021, 91: 949–964”

Numerical analysis of Carreau fluid flow over a vertical porous microchannel with entropy generation

This study investigates novel aspects of entropy generation in fully developed heat transport of Carreau fluid in a porous vertical microchannel. Consequences of thermal radiation and viscous heating are included in the thermal energy equation. The no-slip velocity and convective heating temperature boundary conditions are also considered. Darcy–Forchheimer model model is also considered. The system is solved using the bvp4c approach to solve a dimensional less two-point boundary value problem derived from the governing equations. The effect of effective factors on the Bejan number, entropy generation rate, temperature, and velocity are depicted in graphs. According to our analysis, increasing values of the Weissenberg number reduce entropy generation on the left and right sides of the channel, whereas the Bejan number improves on both sides of the channel and is highest in the middle. The fluid transport in a microchannel is enhanced by the pressure gradient. Because of the boundary conditions of convection heating at the microchannel walls, entropy production is at its maximum. Furthermore, the magnitude of the Bejan number is lessened due to a stronger viscous heating mechanism, whereas entropy production gets larger. The results were compared to those previously reported in the literature as a limiting case of the problem, and they were found to be in excellent agreement.

Numerical analysis of landslide-generated debris flow on July 3, 2021 in Izu Mountain area, Shizuoka County, Japan

Numerical analysis of landslide-generated debris flow on July 3, 2021 in Izu Mountain area, Shizuoka County, Japan

Numerical Analysis of Boundary Layer Flow and Heat Transfer over a Shrinking Cylinder

The investigation concerning the movement of the viscous fluid and heat transfer rate when the cylinder shrinks is carried out. The role of curvature parameter and effect of cylinder parameter on skin friction and heat transfer rate were studied. The existence of a dual solution is observed and subsequently identifies which solution is stable. By using the similarity transformation, the boundary layer equations are transformed into nonlinear ordinary differential equations which are then solved numerically using bvp4c in MATLAB. The results for the skin friction coefficient, temperature gradient coefficient as well as velocity and temperature profiles are presented graphically. The effects of mass suction parameter and curvature parameter on flow and heat transfer characteristics are also presented. It is found that the dual solution existed when mass suction parameter greater or equal to 2. Cylinder surface diminished the performance of skin friction coefficient and heat transfer rate. The stability analysis result is performed to verify that the upper branch solution is stable and physically meaningful.

Experimental and numerical analyses of fluid flow inside additively manufactured and smoothed cooling channels

The surface roughness can be considered one of the main drawbacks of the Laser Powder Bed Fusion (LPBF) technology applied to thermal applications. Favero et al. [1] experimentally and numerically demonstrated that the surface roughness of printed copper channels deeply affects their fluid dynamic performance and limits the predictive capabilities of the CFD tools. The authors proposed a methodology to calibrate the numerical tools in turbulent flow. However, the problem remains unsolved because the printed copper channels exhibit remarkably higher pressure drops when compared to conventional smooth channels, hindering the proper deployment of the technology in the thermal sector. This paper proves how it is possible to smooth the internal walls of channels obtained via LPBF to reduce the surface roughness. In fact, the chemical milling process is proposed and applied. The smoothed channels showed a fluid dynamic behaviour similar to the conventional ones. Finally, by coupling Computer Tomography to the CFD tool, the fluid dynamic behaviour inside the smoothed channels is fairly predicted, confirming that the surface roughness and the channel dimensions are the controlling parameters of the fluid dynamic performance of channels printed via LPBF.

Numerical and Experimental Analysis of Heat Flow at Window-to-Wall Interface

External walls have a great influence on the thermal and humidity conditions in buildings as well as on the possibility of reducing energy consumption. While the structural and material aspects of walls and windows are well known, obtaining a tight connection to reduce thermal bridges between the window and walls still poses a significant problem. Therefore, a new window installation system proposed by the authors, eliminating linear and point thermal bridges at the window-to-wall interface, opens a pathway for lowering energy consumption in buildings and increasing thermal comfort and thermal efficiency. To prove the effectiveness of this system, numerical and experimental analyses of heat flow through an outer wall with a window were carried out. The numerical analyses were performed using the TRISCO software package. It was shown that the proposed solution eliminated the occurrence of linear thermal bridges at the window-to-wall interface (a linear heat transmittance coefficient Ψ ≈ 0.007, which meets the requirements of the passive house, was obtained). Thus, heat losses were reduced by nearly eight times compared to conventional installation systems. Numerical calculations were experimentally verified.

Numerical analysis of debris flows along the Sichuan-Tibet railway based on an improved 3D sphere DDA model and UAV-based photogrammetry

This paper develops an improved three-dimensional sphere discontinuous deformation analysis (SDDA) model and uses UAV-based photogrammetry to enable SDDA to numerically analyze potential long-runout debris flows in Zheduotang area along the Sichuan-Tibet railway. First, the original SDDA is improved by proposing a sphere-sphere bonding algorithm to bond spheres with tetrahedral layout to form four-sphere clusters to approximate non-sphere particles in debris flow. Second, the capacity of the improved SDDA is verified by comparing modelling results with four groups of laboratory tests of granular flow. Third, UAV-based photogrammetry is used to obtain the real morphology of the extremely complex terrain surface of Zheduotang area which is finally transferred into a large number of triangular faces as the fixed boundary faces of SDDA. Then, three potential debris flow scenarios on this terrain surface are numerically studied, and some suggestions for engineering disaster prevention are drawn. Model performance shows that, the improved SDDA is a feasible tool to simulate debris flows. With the help of UAV-based photogrammetry, it shows significantly helpful for geohazard prevention for infrastructures in mountainous areas like the Sichuan-Tibet railway.

Numerical and experimental analysis of temperature distribution and melt flow in fiber laser welding of Inconel 625

In these days, laser is a useful and valuable tool. Low input heat, speed, accuracy, and high controllability of laser welding have led to widespread use in various industries. Nickel-based superalloys are creep-resistant materials used in high-temperature conditions. Also, these alloys have high strength, fatigue, and suitable corrosion resistance. Inconel 625 is a material that is strengthened by a complex deposition mechanism. Therefore, the parameters related to laser welding affect the microstructure and mechanical properties. Therefore, in this study, the effect of fiber laser welding parameters on temperature distribution, weld bead dimensions, melt flow velocity, and microstructure was investigated by finite volume and experimental methods. In order to detect the temperature history during continuous laser welding, two thermocouples were considered at a distance of 2 mm from the welding line. The heat energy from the laser beam was modeled as surface and volumetric heat flux. The results of numerical simulation showed that Marangoni stress and buoyancy force are the most important factors in the formation of the flow of liquid metal. Enhancing the laser power to 400 W led to the expansion of the width of the molten pool by 1.44 mm, which was in good agreement with the experimental results. Experimental results also showed that increasing the temperature from 500 °C around the molten pond leads to the formation of a coarse-grained austenitic structure.

Experimental and Numerical Flow Analysis of an Engine Realistic State-of-the-Art Turbine Rear Structure

Abstract This paper presents experimental and numerical CFD studies of the aerodynamics of a turbine rear structure (TRS). The TRS test geometry is an engine-realistic state-of-the-art design with a polygonal outer case, recessed engine mount bumps, and three different vane types: regular vanes, bump vanes in bump sectors, and thick vanes. Using three different sector types simultaneously was found to be crucial for the inlet boundary conditions. Experiments were performed in a modern rotating test facility with a low-pressure turbine (LPT) stage upstream of the TRS. A Reynolds number of 350,000 was used, representative of a TRS in a narrow-body geared turbofan engine. The TRS performance was analyzed both at on- and off-design conditions, and a thorough side-by-side comparison of CFD and experiments was performed. Static-pressure distributions, turning and outlet flow-angles, wakes and losses, and surface-flow visualizations and outlet total pressure contours are presented. The thick vane showed good aerodynamic performance, similar to the regular vane. For the bump vane, the mount bumps were found to generate additional local separations and secondary flows, resulting in extra losses. In the regions with strong secondary flows, CFD over-predicts the wakes, whereas the wakes around midspan, where secondary flows have a smaller influence, are predicted well.

On numerical analysis of hydromagnetic radiative Jeffery nanofluid flow by variable thickness surface with activation energy and unsteadiness aspects

The mass and thermal flow of an unsteady Jeffery fluid over a surface having variable thickness with the presence of magneto-hydrodynamics is considered here. For this physical problem, we develop a mathematical formulation using Buongiorno’s model for the Jeffery fluid. Characteristics of pedesis motion and thermo-migration of nanoparticles with the thermal link of heat source/sink are also examined. An arrangement of similarity variables is introduced to transform the transport equations into solvable forms in Cartesian configuration. A numerical solution of the differential system is obtained by using the algorithm of Runge–Kutta-Fehlberg fourth-fifth (RKF-45) method. Physical interpretations of obtained outcomes are established with the help of various plots, isotherms, and streamlines. Flow velocity reduces wall-thickness and unsteadiness parameters. Temperature enhances with the advances of radiation parameters, whereas regresses for the progression of Deborah number. Concentration improves with the progression of the activation energy parameter. Nusselt number condenses for velocity index and Eckert number. A comparison benchmark is also presented for solution validation.

Numerical analysis of heating aerosol carbon nanofluid flow in a power plant recupesrator with considering ash fouling: a deep learning approach

The main goal of this research is to optimize a corrugated high-temperature helical recuperator filled with aerosol-carbon-black nanofluid. This heat exchanger has inner semi-sphere-shaped corrugations with different diameters. In this study, the related effects of different geometric parameters according to the heat-hydraulic performance of the studied helical heat exchanger are analyzed. Moreover, to select the optimal model, the hydraulics-thermal index is examined and its maximum value is introduced as the optimal model. The Discrete Phase, Model (DPM) approach is also used to model multi-phase currents. In order to numerically simulate and solving the governing equations, the Ansys Fluent software, SIMPLE algorithm and the finite volume method were used. As it is realized, the helical corrugated recuperator with corrugation diameter of d=10mm and filled with nanofluid (NF) with volume concentration of φ=0.7% has the maximum thermal-hydraulic performance evaluation criteria. Then, a deep learning method is applied to data in order to obtain the average Nusselt number (Nuav), the pressure drop (ΔP) between outlet and inlet, the friction factor (f), and the PEC for all values of the volume fraction, mass flow rate, and turbulators diameter within the examined range. To this end, an Artificial Neural Network (ANN) with one hidden-layer is employed. The results indicate that the ANN can model the investigated phenomenon with acceptable level of precision.

Numerical analysis of hydromagnetic mixed convective flow in an internally heated vertical porous layer using thermal nonequilibrium model

AbstractThe inertial and viscous effects on mixed hydromagnetic convection in a vertical porous channel using a local thermal nonequilibrium model with uniformly distributed internal sources are analyzed. The flow in the porous medium is described by the Brinkman–Forchheimer extension of Darcy's momentum equation. The vertical rigid boundaries are maintained at constant but different temperatures and a uniform magnetic field is applied across the porous layer. The governing equations are solved numerically by the finite element method and analytically by the perturbation method. The influence of governing parameters on the flow variables and heat transfer is discussed. An extensive study designates that an increase in the Darcy number enhances the velocity distribution due to increased permeability of the medium while the opposite trend is observed with increasing Hartmann number due to the increased retarding nature of Lorentz force. The presence of an external heat source has a notable impact on the temperature gradient of the fluid, which results in an increase in temperature distribution and thermal state of the fluid. A quantitative increase in heat transfer coefficient results in an increase of fluid temperature toward the electrically nonconducting wall, and as the fluid moves toward the electrically conducting wall the fluid temperature decreases. The results indicate that the Nusselt number declines with an increase in the solid internal heat generation parameter.