scholarly journals The study of the numerical diffusion in computational calculation

2020 ◽  
Vol 310 ◽  
pp. 00039
Author(s):  
Kamila Kotrasova ◽  
Vladimira Michalcova
Keyword(s):  
Heat Transfer ◽  
Differential Equation ◽  
Numerical Simulation ◽  
Continuity Equation ◽  
Cfd Simulation ◽  
Flow Process ◽  
Ansys Fluent ◽  
Numerical Diffusion ◽  
Mesh Density ◽  
Computational Calculation

The numerical simulation of flow process and heat transfer phenomena demands the solution of continuous differential equation and energy-conservation equations coupled with the continuity equation. The choosing of computation parameters in numerical simulation of computation domain have influence on accuracy of obtained results. The choose parameters, as mesh density, mesh type and computation procedures, for the numerical diffusion of computation domain were analysed and compared. The CFD simulation in ANSYS – Fluent was used for numerical simulation of 3D stational temperature flow of the computation domain.

scholarly journals Numerical Modelling Of Humid Air Flow Around A Porous Body

2015 ◽  
Vol 9 (3) ◽  
pp. 161-166
Author(s):  
Aneta Bohojło-Wiśniewska
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Porous Medium ◽  
Numerical Modelling ◽  
Chinese Cabbage ◽  
Air Flow ◽  
Transfer Model ◽  
Humid Air ◽  
Ansys Fluent ◽  
Complex Heat Transfer

Summary This paper presents an example of humid air flow around a single head of Chinese cabbage under conditions of complex heat transfer. This kind of numerical simulation allows us to create a heat and humidity transfer model between the Chinese cabbage and the flowing humid air. The calculations utilize the heat transfer model in porous medium, which includes the temperature difference between the solid (vegetable tissue) and fluid (air) phases of the porous medium. Modelling and calculations were performed in ANSYS Fluent 14.5 software.

scholarly journals The Numerical Diffusion Effect on the CFD Simulation Accuracy of Velocity and Temperature Field for the Application of Sustainable Architecture Methodology

2020 ◽  
Vol 12 (23) ◽  
pp. 10173
Author(s):  
Vladimíra Michalcová ◽  
Kamila Kotrasová
Keyword(s):  
Temperature Field ◽  
Cfd Simulation ◽  
Flow Direction ◽  
Three Dimensional ◽  
Stationary Flow ◽  
Navier Stokes ◽  
Ansys Fluent ◽  
Simulation Accuracy ◽  
Numerical Diffusion ◽  
Diffusion Temperature

Numerical simulation of fluid flow and heat or mass transfer phenomenon requires numerical solution of Navier–Stokes and energy-conservation equations, together with the continuity equation. The basic problem of solving general transport equations by the Finite Volume Method (FVM) is the exact calculation of the transport quantity. Numerical or false diffusion is a phenomenon of inserting errors in calculations that threaten the accuracy of the computational solution. The paper compares the physical accuracy of the calculation in the Computational Fluid Dynamics (CFD) code in Ansys Fluent using the offered discretization calculation schemes, methods of solving the gradients of the transport quantity on the cell walls, and the influence of the mesh type. The paper offers possibilities on how to reduce numerical errors. In the calculation area, the sharp boundary of two areas with different temperatures is created in the flow direction. The three-dimensional (3D) stationary flow of the fictitious gas is simulated using FVM so that only advective transfer, in terms of momentum and heat, arises. The subject of the study is to determine the level of numerical diffusion (temperature field scattering) and to evaluate the values of the transport quantity (temperature), which are outside the range of specified boundary conditions at variously set calculation parameters.

Numerical Simulation of Electrohydrodynamic (EHD) Atomization in the Cone-Jet Mode

2013 ◽  
Vol 325-326 ◽  
pp. 180-185 ◽  
Author(s):  
Abdolkarim Najjaran ◽  
Reza Ebrahimi ◽  
Morteza Rahmanpoor ◽  
Ahmad Najjaran
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Ambient Temperature ◽  
Deposition Rate ◽  
Low Cost ◽  
High Deposition Rate ◽  
Deposition Technique ◽  
Enhanced Heat Transfer ◽  
Ansys Fluent ◽  
Set Up

Electrohydrodynamic (EHD) has been applied in many areas, such as EHD atomization, EHD enhanced heat transfer, EHD pump, electrospray nanotechnology, etc. EHD atomization is a promising materials deposition technique as it allows uniform and regular deposition, and offers a range of other advantages, such as low cost compared with other current techniques, easy set-up, high deposition rate, and ambient temperature. Simulation is carried out using ANSYS FLUENT system. The approach in this work was to simultaneously solve the coupled (EHD) and electrostatic equations. The fields of velocities and pressure, as well as electric characteristics of EHD flows, are calculated. The model does not include a droplet break-up model.

scholarly journals Earth Air Tunnel Heat Exchanger for Building Cooling and Heating

2021 ◽  
Author(s):  
Nasim Hasan ◽  
Mohd Arif ◽  
Mohaideen Abdul Khader
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Numerical Algorithms ◽  
Ansys Fluent ◽  
Helical Pipe ◽  
Complex Fluid ◽  
Set Up ◽  
Building Cooling

The computational fluid dynamic (CFD) is an influential method for measuring Heat transfer profiles for typical meteorological years. CFD codes are managed by numerical algorithms that may undertake fluid glide headaches. CFD offers the numerical results of partial differential equations with main airflow and heat transfer in a discretized association. The complex fluid glide and the warmth transfer publications worried in any heat exchanger can be determined with the help of the CFD software program (Ansys Fluent). A study states and framework which implicitly rely on the computational fluid dynamics, which is being formulated for computing the efficiency-related parameters of the thermal part and the capability of the EATHE system for cooling. A CFD simulation program is being used for modeling the system. The framework is being validated with the help of the simulation set-up. A thermal model was developed to analyze thermal energy accumulated in soil/ground for the purpose of room cooling/heating of buildings in the desert (hot and dry) climate of the Bikaner region. In this study, the optimization of EATHE design has been performed for finding the thermal performance of straight, spiral, and helical pipe earth air tunnel heat exchanger and Heat transfer rate for helical pipe was found maximum among all designs.

scholarly journals Design improvement of an airbox for a passenger vehicle

2021 ◽  
Vol 2120 (1) ◽  
pp. 012010
Author(s):  
J Tan ◽  
N Z Abu Bakar
Keyword(s):  
Numerical Simulation ◽  
Pressure Drop ◽  
Simulation Model ◽  
Cfd Simulation ◽  
Pollutant Emissions ◽  
Passenger Vehicle ◽  
Repeated Testing ◽  
Road Transportation ◽  
Ansys Fluent ◽  
Testing Cost

Abstract The purpose of an airbox is to provide the engine with a clean air flow for combustion. The high velocity of the fluid flow across the airbox will create a pressure drop resulting a decline in the vehicle’s performance. This project collaborates with an Original Equipment Manufacturer (OEM) to develop a numerical simulation model for a new airbox design and to compare its pressure drop with OEM production design. Reducing the pressure drop across the airbox can increase the efficiency of a vehicle, hence, reducing CO2 emissions. This research focuses on the passenger type vehicle as it is the highest source of carbon dioxide (CO2) being emitted for road transportation and these pollutant emissions have also caused many health problems on human. ANSYS Fluent program was used to carry out Computational Fluid Dynamics (CFD) simulation for both OEM and the new design. Then, the same simulation setup was used for the new design. The inlet size of the new design is larger when compared to the OEM design. After analysing both models, it was determined that the main reason behind the pressure loss was caused by the shape of the airbox and turbulent flow inside. The new airbox design shows reduction of 96% in the pressure drop within it and in return, enhancing the performance of the passenger vehicle. This conclude that numerical simulation model is able to provide a good indicator for the designer to choose the best design and proceed with fabrication and conduct actual test, thus saving a lot of prototyping and repeated testing cost.

Numerical Simulation of Flow Field and Heat Transfer inside a New Enhanced Tube

2014 ◽  
Vol 513-517 ◽  
pp. 2629-2634
Author(s):  
Cheng Long Xu ◽  
Wei Jun Liu ◽  
Wei Ping Hu
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Field Synergy ◽  
Ansys Fluent ◽  
Flow And Heat Transfer ◽  
Exhaust Heat ◽  
Optimal Value ◽  
Enhanced Tube ◽  
Plain Tube ◽  
Simplec Algorithm

A numerical simulation was carried out for the flow and heat transfer in the Double-Inclined Streamlined Ribs tube (DISR tube) which is used in the automobile exhaust heat recovery. This paper is aimed to find the optimum ribs parameters for best heat transfer perfomance. The solution was calculated by ANSYS/FLUENT and the SIMPLEC algorithm was used for the velocity-pressure coupling. The results shows that the optimal value of DISR tube is rib length (l=38mm), rib inclined degree (α=45o), rib height (h=2.5mm) and rib pitch (P=60mm). The heat transfer in the DISR tube is enhanced 72.6% on average compared with a plain tube and the friction factor increases 180.9% on average at Re=12000~50000. In the DISR tube, the field synergy angle reduce from 90° to 80° and the heat transfer is enhanced significantly. The paper shows that the field synergy angle declines greatly near every ribs, and this is the chief reason for the heat transfer enhancement.

Sensitivity of Reduced Kinetic Models: The CFD Simulation of SCO2 Oxy-Combustion

2018 ◽  
Author(s):  
Zefang Liu ◽  
Xiang Gao ◽  
Miad Karimi ◽  
Bradley Ochs ◽  
Vishal Acharya ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Kinetic Model ◽  
Kinetic Models ◽  
Equivalence Ratio ◽  
Cfd Simulation ◽  
Selection Algorithm ◽  
Cfd Simulations ◽  
Ansys Fluent ◽  
Jet In Crossflow ◽  
Autoignition Delay

Current research on supercritical carbon dioxide (SCO2) oxy-combustion is lacking studies on the performance of kinetic models. An optimized 13 species kinetic model is proposed in the present work for CH4/O2/CO2 oxy-combustion. This 13 species kinetic model is developed based on the detailed USC Mech II mechanism with the Global Pathway Selection algorithm, and then optimized with a genetic algorithm covering conditions of pressure from 150 atm to 300 atm, temperature from 900 K to 1800 K and equivalence ratio from 0.7 to 1.3. The autoignition of 13 species kinetic model presents less than 12% error relative to that of the USC Mech II. The performance of the proposed kinetic model is evaluated using a generic jet in crossflow combustor. Simulations at identical conditions are conducted in ANSYS Fluent for both the 13 species model and a global 5 species model. Results were then compared to evaluate the sensitivity of these two kinetic models to the CFD simulations. The results show a better mixing between the fuel and the oxygen, a longer autoignition delay and a more reasonable temperature distribution using the 13 species kinetic model. It is indicating the importance of choice on kinetic models in numerical simulation.

scholarly journals CFD Simulation of Heat Transfer and Turbulent Fluid Flow over a Double Forward-Facing Step

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Hussein Togun ◽  
Ahmed Jassim Shkarah ◽  
S. N. Kazi ◽  
A. Badarudin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Cfd Simulation ◽  
Step Height ◽  
Ansys Fluent ◽  
Contour Maps ◽  
Before And After ◽  
Forward Facing Step ◽  
Energy Equations

Heat transfer and turbulent water flow over a double forward-facing step were investigated numerically. The finite volume method was used to solve the corresponding continuity, momentum, and energy equations using theK-εmodel. Three cases, corresponding to three different step heights, were investigated for Reynolds numbers ranging from 30,000 to 100,000 and temperatures ranging from 313 to 343 K. The bottom of the wall was heated, whereas the top was insulated. The results show that the Nusselt number increased with the Reynolds number and step height. The maximum Nusselt number was observed for case 3, with a Reynolds number of 100,000 and temperature of 343 K, occurring at the second step. The behavior of the Nusselt number was similar for all cases at a given Reynolds number and temperature. A recirculation zone was observed before and after the first and second steps in the contour maps of the velocity field. In addition, the results indicate that the coefficient pressure increased with increasing Reynolds number and step height. ANSYS FLUENT 14 (CFD) software was employed to run the simulations.

Numerical Simulation and Structure Optimization of Converter Gas Evaporative Cooler

2013 ◽  
Author(s):  
Zeyi Jiang ◽  
Pengyuan Chen ◽  
Pan Liu ◽  
Guanghe Tian
Keyword(s):  
Numerical Simulation ◽  
Mass Transfer ◽  
Cfd Simulation ◽  
Engineering Application ◽  
Discrete Phase Model ◽  
Engineering Project ◽  
Two Phase ◽  
Flow Process ◽  
Evaporative Cooler ◽  
Cfd Method

In Lurgi-Thyssen dedusting system of steelmaking converter, the evaporative cooler represents a crucial operating unit, in which the hot dust-laden flue gas has to be cooled by saturation with water. The cooling process of the gas consists of gas-liquid two phase flow and interphase heat and mass transfer. In this paper, k-epsilon standard equations and Lagrange discrete phase model are employed to describe the gas turbulent flow and the heat/mass transfer with droplet evaporation individually. The computational fluid dynamics (CFD) simulation for practical engineering project shows that the large-flux cooling gas is commonly constructed in a non-uniform flow caused by the sharp turnings at the inlet and outlet channels. The unevenness of velocity distribution and the effective cooling height are defined in this paper to evaluate the cooling flow process. A series of newly designed structures with guide plate are investigated by CFD method to eliminate the problems with the non-uniformity. The results of numerical simulation show that optimal designed guide ring plate could improve the flow uniformity and the heat transfer. The investigations have been used to guide the engineering application.

scholarly journals Numerical Study of Heat Transfer and Exergy Analysis of Shell and Double Tube Heat Exchanger

2020 ◽  
Vol 38 (4) ◽  
pp. 925-932
Author(s):  
Ruslan S. Abdulrahman ◽  
Farah A. Ibrahim ◽  
Safaa H. Faisel
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Exchanger ◽  
3D Model ◽  
Exergy Analysis ◽  
Numerical Study ◽  
Ansys Fluent ◽  
Tube Heat Exchanger ◽  
Computational Fluid Dynamics Cfd ◽  
High Reynolds

The heat exchanger (HX) plays a key role for several industries, to reduce the energy consumption by rising heat transfer rate through heat exchanger. In this study, numerical simulation of shell and double tube heat exchanger without and with baffles is analyzed to evaluate the heat transfer and exergy analysis. A numerical simulation of 3D model with turbulent flow at the range (4000-12000) is performed with commercial computational fluid dynamics (CFD) software ANSYS (Fluent). The circular vents baffles model is used at the side of the shell. The simulation results show that the circular vents on the baffles of the heat exchanger have a significant impact on thermal- hydraulic performance and exergy analysis. Also, the results show that the heat exchanger effectiveness with baffles increases by 17% at high Reynolds number comparing with heat exchanger without baffles. Besides, the highest value of exergy loss reached to 42W with baffles presence. Finally, it is concluded that the heat exchanger with baffles gives better hydraulic and thermal performance than that of heat exchanger without baffles.

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