Numerical Analysis Of Flow Research Articles

Numerical analysis of hydrothermal flow and heat transfer inside a cavity formed due to faults causing earthquakes

This article studies fluid dynamics and convection of the geothermal system. Earthquakes cause faults. Fault zones come up with the pathways for fluid convection. These paths have different characteristics and space distribution, causing the challenge to investigate the geothermal system. The cavity considered in the study is normally found in energy reservoirs. An unsteady, incompressible, and laminar flow along with convection is studied. The finite element method (FEM) is operated to study the flow and heat transfer governed by continuity equations, Navier-Stokes equations, and temperature equations. These equations are tackled with the finite element method. The streamlines and isothermal contours for the problem under discussion are displayed in the Results section. It is observed that the Nusselt number and velocity of the fluid increase with the increased Grashof number.

Numerical analysis for two-phase flow with non-equilibrium capillary pressure in anisotropic porous media

Numerical analysis for two-phase flow with non-equilibrium capillary pressure in anisotropic porous media

A model and its experiment using compressed cold air to clean the active surface of a grinding wheel during sharping of a hob cutter

The removal of chips, which is produced during the grinding process and forms, among other things, cloggings on the grinding wheel active surface (GWAS), is key to extending wheel life and achieving low surface roughness. Currently, as a result of the minimum quantity lubrication (MQL) method of delivery coolant into the cutting zone, the support of chips removal with a stream of cooled compressed air (CCA) is becoming particularly important. Among other things, the angle of the CCA jet delivery nozzle with respect to the GWAS is responsible for the removal efficiency, which has to be considered individually for each grinding process variation, and experimental tests alone do not give an idea of the CCA jet flow. In the present study, a numerical flow analysis (using the computational fluid dynamics method) of cooled compressed air in the grinding zone during the sharpening of a hob cutter face was carried out. The results of the numerical simulations were verified experimentally by determining the percentage of the grinding wheel clogging Z%. The experimental results confirmed the conclusions from the numerical analysis regarding the most favorable angle of the CCA nozzle. The Z% = 5.3 clogging index obtained when grinding with the CCA nozzle set at an angle of 45° is 2.5 times lower than the Z% = 13.5 index determined for the most favorable setting of the MQL nozzle. Simultaneous delivery of CCA and air-oil aerosol using the MQL-CCA method resulted in the lowest Z% = 2.5, comparable to the Z% = 2.0 obtained for a grinding wheel operating under cooling conditions with a water-based oil emulsion delivered by the flood method (WET).

Numerical Investigation on Characteristics of Fluid Flow Over Cavity in a Parallel Channel at Low Reynolds Numbers

The database management output system is interesting and available in the numerical analysis of fluid flow, especially for a fluid flowing past a cavity inside a channel. The aim of the current study is to investigate numerical simulations characteristic of fluid flowing over a cavity in a parallel channel at low Reynolds numbers and to predict reduced energy. Computer Fluid Dynamic (CFD) is utilized to solve two-dimensional low Reynolds Navier-Stoke equations with support from Gambit software, which incorporates a simulation modelling suite in the meshing model. The numerical simulations were carried out by fluid such as water for the Reynolds numbers of 50 and 1000 and for cavity aspect ratio, W/H, of 1/3, 1/2, 1, 2, and 3. The normal mean velocity input is unity. This investigation indicated that changing cavities aspect ratio influences vortex flow significantly. Besides, the study found that the aspect ratio of cavities and Reynolds numbers influence total pressure and temperature output significantly and are important for most fluid dynamic problems. Finally, the optimal reduced pressure in a channel and optimal design cavities geometries yield better results.

Numerical analysis of ventilated cavitating flow around an axisymmetric object with different discharged temperature conditions

Nowadays, with the widespread use of modern technology in underwater vehicles, particularly in naval applications, the artificial gas ejected from ventilated holes is normally heated because of engine operations. However, the dynamics of ventilated hot gas have not yet been fully studied. In this study, the cavitating flow around an axisymmetric body with different ventilated temperatures was numerically investigated. A fully compressible mixture model based on a homogeneous multiphase approach was employed. A high-order accuracy flow solver based on the numerical models of a dual-time preconditioning technique, a sharp interface-capturing scheme, and an enhanced cavitation model was used to examine the effects of temperature on the cavitating flow. First, the numerical results were validated by comparison with available experimental data of cavitating flow around a conical cavitator. Reasonable agreements on the cavity shape, cavity length, and cavity thickness were achieved. The solver was then applied in simulations to analyze the development of the ventilated cavity, including the cavity formation at the early stage, the re-entrant jet phenomenon, and the cavity shedding mechanism. In addition, the effects of ventilated temperatures on the cavity length and cavity thickness were studied. Further insight into the distributions of the flow field inside the cavity, and the instability of the gas-water interface when temperature increases were also provided.

Numerical investigation of entropy hydraulic loss analysis and vortical structure suppression in mixed flow pump device under lateral inflow

To investigate the influence of the lateral inflow on the vortical structures and hydraulic losses inside the mixed-flow pump, entropy production, and Q-criterion were applied to numerical simulation analysis of transient flow. Three inflow runner schemes were designed to compare the effects of the middle-isolated pier and rear wall of the “ω” structure on restraining the occurrence and transmission of a vortex and stabilizing the internal flow state of the pump device. The results showed that when the inflow condition transformed from parallel inflow to lateral inflow, the design efficiency and head deviated toward the over-load flow rate, and the maximum deviations were obtained under the over-load flow rate, reaching 4.79% and 50.35%, respectively. The hydraulic losses and vortical structures increased to a large extent, influenced by the lateral inflow, particularly the flow region near the impeller hub. The setting of the vortex suppression facilities effectively reduced the deviation ratios in the design efficiency and head, which decreased to 1.31% and 7.59%, respectively. The vorticity intensity and entropy dissipation rate were also significantly decreased. By contrast, the rear wall of the “ω” structure had a greater stabilization effect on the internal flow patterns than that of the middle-isolated pier.

Numerical analysis of viscoelastic Maxwell fluid flow through a radiative axisymmetric semi‐porous channel

AbstractThe non‐Newtonian fluids have abundant implications in versatile fields of chemical, mechanical, and biological engineering. Furthermore, the non‐Newtonian fluids flowing through the porous medium are very useful in petroleum and industrial engineering. Heat transport analysis with radiation has major appliances in fusion reactors, heat exchangers, solar energy, aircrafts engines, turbine cooling, and many others. Having all these important appliances in view, the present study is focused on the heat transfer analysis of an incompressible two‐dimensional viscoelastic magnetohydrodynamic Maxwell non‐Newtonian liquid flow in a porous space. The magnetic field is uniformly applied tangential to the flow direction and the lower‐channel wall is heated by induction as a consequence of the Lorentz force. The effect of thermal radiation is taken to foresee the physical occurrence of heat kinetics from an applied point of view. Similarity transformation is considered in reducing the governing partial differential equations into ordinary differential equations and a numerical solution is computed using the shooting technique. The results obtained are compared with the published literature. The effects of flow quantities are illustrated graphically and analyzed with physical meaning. In view of engineering applications, the effects of Reynolds on skin friction coefficient and rate of heat transfer are presented.

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.