Commercial Software Package FLUENT Research Articles

Numerical Study of Heat Transfer and Fluid Flow over Circular Cylinders in 2D Cross Flow

Among the many experiments Which deals with the study of the characteristics of flow, a numerical study of flow air (Pr=0.71) crosses a circular cylinder is conducted. Variations in flow and thermal characteristics such as average Nusselt number, local pressure coefficient and drag coefficient are presented around the cylinders for Reynold numbers ranging from 100 to 5000 by solving the incompressible two-dimensional unsteady Navier-Stokes and energy equations. Commercial software package FLUENT 19 is applied to solve the equations. The diameter of the circle is D = 20 mm, the width is 20 times the diameter of the cylinder. The results obtained are compared with data of previous study for Nusselt Number values showed acceptable agreement. The results of the drag coefficient confirm a noticeable decrease in the transition from low values of Reynolds numbers to the high values.

Numerical Study Mixed Convection in a Channel with an Open Cavity Involving Rotary Cylinder

A numerical study of mixed convection inside a horizontal channel with an open square cavity that includes an adiabatic rotating cylinder. The bottom wall of the cavity is heated at a constant temperature, and the remaining walls are adiabatic. The flow is incompressible, laminar and steady state. The equations of continuity, momentum and energy are solved numerically using computational fluid dynamics (CFD) with the commercial software package FLUENT 2019 R1. Reynolds number values of 50, 100 and 150, the Richardson number (0.1 ≤ Ri ≤ 10) and the angular velocity (ω) of cylinder is (0.5 ≤ ω ≤ 4) rad/sec with direction counter clockwise. Prandtl number for air flow is (Pr = 0.7). The results are presented in terms of streamlines, isotherms, and the average Nusselt value is given over the heated bottom cavity. The combined effects of natural and forced convection in and out of the cavity were obtained. The results showed that at low Richardson values, Ri = 0.1 the effect of buoyancy force is neglected. The effect of increasing the cylinder speed is clearly noticeable at low Reynolds values, Re = 50. Average Nusselt values increase with increasing rotational speed of the cylinder for all Richardson values.

Numerical investigation on the convection heat transfer and drag reduction by utilizing the designed flow controlling blades on a smart sustainable house

The development of the boundary layer leading to separation of the flow from the surface along with the formation of the wake regions dramatically increases the overall convective heat transfer coefficient and the exerted drag force on the body. Sustainable building designs are usually encountered with energy issues mainly related to heat loss through the facades due to convective heat transfer and aerodynamic loading problems on the structure due to severe drag forces on facades. Flow control has been demonstrated as a promising tool for reducing wake intensity and preventing flow separation in different areas of aerospace and mechanical engineering. This paper numerically investigates the feasibility and efficiency of utilizing a novel idea based on locating flow controlling blades (FCBs), designed by the Department of Building Aerodynamics of the Solar Decathlon China 2013 (SDC 2013) Team of Iran, in the periphery of the external facades of the house in order to control the external flow and make it more streamlined than the real case of wind around approximately cubic shaped houses, while the objective is to reduce the convection heat loss from the walls and drag force exerted on them. As a case study, the smart sustainable house (Shāremān) was designed by the RTEOPT (Research Team for Energy Optimization and Passive-house Technologies) and participated in the SDC 2013 held by the U.S. DOE and National Energy Administration of China is presented. A 2D incompressible steady computational fluid dynamics solver, based on the finite volume method in the available commercial software package Fluent, is employed, and wind directions varying from 0 to 330 are resolved. The numerical results show an average reduction of about 15.6% for convective heat transfer coefficient over 12 different conditions; also, a decrease of about 4.8% is observed for the pressure difference between the stagnation point and the opposing corresponding point behind the body of the house.

CFD analysis of fluid flow inside a pentroof combustion chamber with different piston shapes

In the present work a study of in-cylinder flow for spark ignition (SI) engine is carried out, for pentroof head piston geometry with four different configurations of the piston crown. The flow pattern is investigated using commercial software package Fluent 6.3 during intake and compression stroke at different engine speeds. The parameters investigated are turbulent kinetic energy (TKE) and tumble ratio. The nature of computed velocity and TKE contours for flat piston combustion chamber is found to be in good agreement with experimental results (Murali et al., 2010). Furthermore, it is found that piston shape significantly affects the velocity and TKE contours of SI engine during the compression stroke. The combustion chamber with trapezoidal piston shows more TKE and tumble ratio when compared to other pistons at 330 crank angle degree, i.e., near TDC during compression, where turbulence is most essential before ignition.

CFD analysis of fluid flow inside a pentroof combustion chamber with different piston shapes

In the present work a study of in-cylinder flow for spark ignition (SI) engine is carried out, for pentroof head piston geometry with four different configurations of the piston crown. The flow pattern is investigated using commercial software package Fluent 6.3 during intake and compression stroke at different engine speeds. The parameters investigated are turbulent kinetic energy (TKE) and tumble ratio. The nature of computed velocity and TKE contours for flat piston combustion chamber is found to be in good agreement with experimental results (Murali et al., 2010). Furthermore, it is found that piston shape significantly affects the velocity and TKE contours of SI engine during the compression stroke. The combustion chamber with trapezoidal piston shows more TKE and tumble ratio when compared to other pistons at 330 crank angle degree, i.e., near TDC during compression, where turbulence is most essential before ignition.

Numerical study of turbulent forced convection in a finned tube with and without CuO nano fluid

Purpose The purpose of this paper is to carry out a numerical investigation to study forced convection for a tube with fins on the inner and outer surfaces with water as the base fluid and adding particles of CuO to have a nanofluid. Design/methodology/approach Three geometries are designed by using Solid Works and the number of inside fins is 20 with height 6 mm and thickness 1 mm. The number of outside fins is 20 with height 12 mm and thickness 1 mm. The length of the tube is 1,000 mm and the inner and outer diameter is 26 and 28 mm, respectively. The annular diameter is 60 mm. The geometries are imported to Gambit where the mesh is chosen and the boundary conditions are specified. The commercial software package Fluent version 14.0 has been used to numerically solve the governing equations for the three cases. Findings The temperature contours for the three models at different air velocities, i.e., 5, 7.5 and 10 m/s and water velocities 0.8, 1 and 3 m/s have been investigated. The enhancement of heat transfer by using CuO nanoparticles has been investigated at different nanofluid concentrations. Originality/value In this paper, a numerical study is presented to analyze internal and external longitudinal finned tubes with water inside and air outside, with and without nano CuO particles.

A numerical study on the nonlinear effects in focused wave modelling and forces on a semi-submerged horizontal cylinder

ABSTRACTThis paper concerns on the propagation of transient wave groups, focusing at one point in time and space to generate large waves. A numerical wave tank is developed based on the commercial software package FLUENT. Velocity inlet method is applied to reproduce the focused waves in this model, and the results are compared with linear and second-order theoretical results. The continuous wavelet transform is employed to analyse the time–frequency characteristics of the focused waves. Forces due to focused waves acting on a semi-submerged horizontal cylinder is investigated and compared with the regular wave sharing with identical wave crest height and trough-to-trough period. Secondary load cycle is observed which may cause “ringing”. This developed model is expected to serve as a basis for strongly nonlinear waves, such as freak waves.

Analysis and numerical simulation of a novel gas–liquid multiphase scroll pump

This paper presents analysis of a novel multiphase scroll pump to transport gas–liquid two-phase mixtures, in which each compression chamber has a flank clearance which forms a pressure unloading gap connected to the discharge port. Therefore, this multiphase scroll pump has the function of unloading gas–liquid mixture pressure automatically during the compression process, so the frequently occurring problem of liquid slugging in displacement multiphase pumps is solved. Hence, safety and reliability are improved. In this paper the working process model of the presented multiphase scroll pump is discussed; and equations of fluid motion and geometry of scroll wrap profiles are given. Grid generation and numerical methods are discussed, and numerical simulation of the working process for a multiphase scroll pump is conducted using the commercial CFD software package Fluent, with results suggesting key parameter values for design of multiphase scroll pumps.

Modelling and experimental studies of a water–gas shift catalytic membrane reactor

A 2-dimensional, axis-symmetric CFD model of a tubular CMR has been developed using a commercial software package FLUENT for the purposes of guiding the design and operation of a HTWGS-CMR for the processing of coal-derived syngas. Development of the model has been approached in a stepwise manner through the successive incorporation of sub-models for the CMR processes. For each step, performance of model was checked and validated against measurements using a prototype CMR with same set-up applied in simulation.The optimum catalyst loading, which yield the maximum CO conversion within targeted operating reactor temperatures (350–450°C), was found to be 11.6kg/(COmol/s) for the inlet syngas temperature of 350°C with a reactor having a 1″ shell diameter. The CMR model was validated experimentally with a simulated coal-derived syngas (64.5% of CO, 33.0% of H2 and 2.5% of CO2 with a 3:1 steam to carbon (S:C) ratio) at a total dry gas flow of 4 LN/min and a feed pressure of 15barg. These tests were performed using a prototype reactor which incorporated with a tubular (0.1mm thick, 150cm2, 3/8″ OD) Pd/Ag23wt% membrane. The CMR model was simulated using a wider range of operating parameters (namely permeation rate, inlet temperature, catalyst loading, pressure at permeate side and S:C ratios) to examine its sensitivity to these variables. Outcomes of these parametric analyses have enhanced our understanding of CMR operation in order to optimise its performance.

CFD analysis of thermal stratification in domestic hot water storage tank during dynamic mode

In this paper, the thermal behavior of a vertical domestic hot water storage tank during the dynamic mode was studied. A 3D computational fluid dynamic (CFD) model was performed using the commercial software package Fluent v6.3. The proposed model was validated with experimental data obtained from the literature. The results of the simulation served to analyze the flow characteristics and the thermal stratification evolution during charging and discharging phases. This study was further extended to explore the effect of varying tank position (horizontal/vertical) on the system performance. A numerical comparison between the two configurations was carried out and performance parameters such as discharge efficiency, Richardson number and stratification efficiency were calculated. A major finding of the above analysis was the presence of two regions of increased thermal mixing in the horizontal tank. The contribution of these two recirculation zones on the destruction of the thermal stratification resulting in a decrease of the overall performance was demonstrated.

Influence of concentration distribution of hydrogen in air on measured flammability limits

There is a clear difference between exiting data on the measured flammability limits of hydrogen-air mixture. The non-uniformity of concentration distribution of hydrogen in air is a contributor to deviations of the upper flammability limit (UFL) and the lower flammability limit (LFL) measured in different experiments. This paper presents a numerical model to simulate the gas mixing process from start to stability, to predict the concentration distribution, and to research the influence of concentration distribution of hydrogen in air on measured UFLs and LFLs. The commercial software package Fluent was used to carry out the numerical simulation for the concentration distribution of hydrogen in air in the vessels with length-to-diameter ratios (L: D) of 1:1, 3:1, 5:1 and 7:1 respectively. Based on the numerical simulation and analysis, the influence of concentration distribution on measured flammability limits was demonstrated for hydrogen in air in the vessel. It is found that the deviations of measured flammability limits of hydrogen in air are the minimum in the vessel with length-to-diameter ratio of 1:1, and augment with the augmentation of vessel length-to-diameter ratio. Moreover, it is presented that the deviations of measured flammability limits of hydrogen in the center of the vessel are lower than that in the top and the bottom.

Design parameter study on the performance of lead-acid batteries

The investigation of design parameters is very helpful for optimizing the capacity of an electrochemical cell, which can be done by both experimental and numerical methods. In this study, a lead-acid battery has been simulated numerically using the CFD commercial software package FLUENT. The governing equations, including conservation of charge in solid and liquid phases and conservation of species, are solved by developing several user defined functions (UDF). The effect of some basic parameters such as electrode porosity, discharge current density, and width of the electrodes and separator on the cell voltage behavior of a lead-acid battery is investigated. It has been shown that increasing the width and porosity of separator has both positive and negative effects on the performance parameters of battery. Furthermore, a thicker PbO2 electrode has a more pronounced effect than a thicker Pb one.

The Effect of Electrode Parameters on Lead-Acid Battery Performance

The investigation of design parameters is greatly helpful to use the optimum capacity of an electrochemical cell, which can be obtained from both experimental and numerical methods. In this study, a lead-acid battery has been simulated numerically using the CFD commercial software package FLUENT. The governing equations, including conservation of charge in solid and liquid phases and conservation of species, are solved by creating user defined functions. The effect of some basic parameters such as electrode porosity, discharge current density and width of the electrodes on the cell voltage behavior of a lead-acid battery is investigated. It has been shown that the increasing of the thickness and porosity of the PbO2electrode has more pronounced effect on the performance of battery than the Pb one.

Thermo-mechanical modeling of dendrite deformation in continuous casting of steel

In the field of modern steelmaking, continuous casting has become the major manufacturing process to handle a wide range of steel grades. An important criterion characterizing the quality of semi-finished cast products is the macrosegregation forming at the centre of these products during solidification. The deformation induced interdendritic melt flow has been identified as the key mechanism for the formation of centreline segregation. Bulging of the solidified strand shell causes deformation of the solidifying dendrites at the casting's centre. Hence, a fundamental knowledge about the solid phase motion during casting processes is crucial to examine segregation phenomena in detail. To investigate dendritic deformation particularly at the strand centre, a thermo-mechanical Finite Element (FE) simulation model is built in the commercial software package ABAQUS. The complex dendritic shape is approximated with a conical model geometry. Varying this geometry allows considering the influence of different centreline solid fractions on the dendrite deformation. A sinusoidal load profile is used to describe bulging of the solid which deforms the dendrites. Based on the strain rates obtained in the FE simulations the dendrite deformation velocity perpendicular to the casting direction is calculated. The velocity presented for different conditions is used as input parameter for computational fluid dynamics (CFD) simulations to investigate macrosegregation formation inside of a continuous casting strand using the commercial software package FLUENT.

Numerical study on the influence mechanism of inlet distortion on the stall margin in a transonic axial rotor

A numerical study is conducted to investigate the influence of inlet flow condition on tip leakage flow (TLF) and stall margin in a transonic axial rotor. A commercial software package FLUENT, is used in the simulation. The rotor investigated in this paper is ND_TAC rotor, which is the rotor of one-stage transonic compressor in the University of Notre Dame. Three varied inlet flow conditions are simulated. The inlet boundary condition with hub distortion provides higher axial velocity for the incoming flow near tip region than that for the clean inflow, while the incoming main flow possesses lower axial velocity near the tip region at tip distortion inlet boundary condition. Among the total pressure ratio curves for the three inlet flow conditions, it is found that the hub distorted inlet boundary condition improves the stall margin, while the tip distorted inlet boundary condition deteriorates compressor stability. The axial location of interface between tip leakage flow (TLF) and incoming main flow (MF) in the tip gap and the axial momentum ratio of TLF to MF are further examined. It is demonstrated that the axial momentum balance is the mechanism for interface movement. The hub distorted inflow could decrease the axial momentum ratio, suppress the movement of the interface between TLF and MF towards blade leading edge plane and thus enhance compressor stability.

Validation of a reduced combustion mechanism for light hydrocarbons

Due to the tremendous costs and difficulties associated with flare measurements, computational fluid dynamics (CFD) simulation could be a viable approach to predict the combustion efficiency as well as VOC/NOx emissions from industrial flaring activities. However, consisting of a large number of reactions and species, most of the detailed kinetic mechanisms for the speciation study of flaring events are too complicated to use in the CFD simulation of industrial-scale flares. A reduced combustion mechanism will lead to improved computational efficiency; however, its fidelity must be validated. This study uses 2D CFD simulations and 1D Chemkin simulations to validate a reduced mechanism developed for the combustion of light hydrocarbons up to C1–C3. This mechanism, consisting of 50 species and 337 reactions, is applicable to C1–C3 hydrocarbons and can be used to predict the combustion efficiency and fate of pollutants released from industrial flares composed of C1–C3 waste gases. In this article, experimental data reported in the literatures have been used to validate the reduced mechanism. The key performance indicators used for comparison are laminar burner-stabilized flames, laminar flame speeds, adiabatic flame temperatures, ignition delay tests, and temperature and concentration profiles of the critical species. The software package CHEMKIN 4.1.1 was used to verify the computational results of laminar flame speeds, adiabatic flame temperatures, and ignition delays. The axial profiles of various critical species are simulated using the commercial CFD software package FLUENT. It is demonstrated that simulation results using this reduced mechanism are in good agreement with reported experimental results.

A comparative study of different CFD-codes for numerical simulation of gas–solid fluidized bed hydrodynamics

The hydrodynamics of a gas–solid fluidized bed reactor were studied numerically. Computational two-dimensional results from open source software packages MFIX and OpenFOAM, and those obtained from the commercial software package Fluent were discussed and compared with numerical and experimental data existing in the literature. The gas–solid flow was simulated applying the multifluid Eulerian–Eulerian model, where the solid phase is treated as a continuum. The solid-phase properties were calculated by using the kinetic theory of granular flow. Momentum exchange coefficients were calculated using the Gidaspow and Syamlal–O’Brien drag functions. Pressure drop and bed expansion ratio predicted by the simulations were in relatively close agreement with benchmark numerical and experimental data sets in the bubbling regime. Contrary to the OpenFOAM predictions, computations with MFIX and Fluent predicted instantaneous and time-average local voidage and velocity profiles which are comparable with results from the literature.

Experimental and numerical investigation of drag force over tubular frustum

There are different ways in order to achieve higher velocity in underwater vehicles. One of these methods is using a body with special form. This paper presents a towing tank based experimental study on drag forces for different Reynolds Numbers of a special underwater model. This paper investigates drag force and drag coefficient in a different flow direction over the model. Obtained experimental results in towing tank are explained. Computational Fluid Dynamic (CFD) simulation also is performed using commercial CFD software package FLUENT 6.3.26. There is a significant decrease in drag coefficient of model moving with small diameter at upstream.

Liquid water flooding in a proton exchange membrane fuel cell cathode with an interdigitated design

SUMMARY In this paper, we studied the liquid water flooding process in the flow field of a proton exchange membrane fuel cell with an interdigitated design by using a multi-phase three-dimensional fuel cell cathode side model with a porous layer. The commercial CFD software package fluent (ANSYS Canonsburg, PA, USA) was used with a user-defined function. The results indicate that the general liquid water flooding process inside of this type of cathode design can be classified into three phases (the porous layer phase, the channel phase, and the drainage phase), and the details of liquid water behavior during this flooding process can be well understood and explained using the air–liquid interaction. Also, a liquid water avalanche phenomenon was discovered in this type of cathode design. Copyright © 2011 John Wiley & Sons, Ltd.

Numerical simulation of heat transfer in a micro channel heat sinks using nanofluids

In this study, a numerical simulation of copper microchannel heatsink (MCHS) using nanofluids as coolants is presented. The nanofluid is a mixture of pure water and nanoscale metallic or nonmetallic particles with various volume fractions. Also, the effects of various volume fractions, volumetric flow rate and various materials of nanoparticles on the performance of MCHS have been developed. A three-dimensional computational fluid dynamics model was developed using the commercial software package FLUENT, to investigate the conjugate fluid flow and heat transfer phenomena in micro channel heatsinks. The results show that the cooling performance of a microchannel heat sink with water based nanofluid containing Al2O3 (vol 8%) is enhanced by about 4.5% compared with micro channel heatsink with pure water. Nanofluids reduce both the thermal resistance and the temperature difference between the top (heated) surface of the MCHS and inlet nanofluid compared with that pure water. The cooling performance of a micro channel heat sink with metal nanofluids improves compared with that of a micro channel heat sink with oxide metal nanofluids because the thermal conductivity of metal nanofluid is higher than oxide metal nanofluids. Micro channel heat sinks with nanofluids are expected to be good candidates as the next generation cooling devices for removing ultra high heat flux.