A backwardfacing step flow in the microchannel with external electric field was investigated numerically by a highorder accuracy upwind compact difference scheme in this work. Simulate flow through backward facing step using icofoam solver in openfoam software tool. Heat transfer and turbulent water flow over a double forwardfacing step were investigated numerically. Simulation of steady, laminar flow over a backwardfacing. Lattice boltzmann method and finite volume method mittal, nitesh, kumar, d santhosh on. The code can be run from the command terminal using the following format. Assessment of turbulence models for turbulent flow over. In this case, the flow is subjected to a sudden increase of crosssectional area, resulting in a separation of flow starting at the point of expansion. I tried the simulation in another software using the following boundary conditions. Forwardbackward facing step flows the study of flow separation is an important issue in fluid dynamics, which results in a total change of the flow field. Although the geometry is very simple, the flow can feature interesting separation regions. Simulation of backward facing step using icofoam solver.
When fluids flow through different geometries, they exhibit different velocity, pressure and flow properties. Turbulent backward facing step studies the bfs flow has been studied intensively for at least four decades and is possibly the most popular benchmark flow. The fluent software was initially developed by fluent inc. Numerical simulation of flow separation over a backwardfacing step. So, in the yesterday, i post here in community some doubts about the rans approach to modeling the turbulent flow through a bfs geometry.
A brief literature survey the study of backwardfacing step. The computational simulation performed in this study is based on the reynolds equations using a technique denominated reynolds average navierstokes rans. Simple 2d backward facing step simulation using converge. High order les for supersonic backwardfacing step flow. Commercial software ansys fluent has been used to resolve the flow field. I was wondering if the time step i have used is correct. Cfd simulation of heat transfer and turbulent fluid flow. The free shear layer evolutions are the dominant factor for. It is a fluid flow solver which can analyse the different flow regimes subsonic to supersonic. One of the objective is to learn the process of solving backward step problem, but the important objective is to understand standards of getting solution for such physics. Given the finite memory and speed of computers, these. This geometry is well suited to study the turbulence behavior under separation, recirculation and reattachment phenomena 11.
The incompressible, turbulent case is validated with the experimental results of driver and seegmiller 1 as archived in the nasa turbulence modeling resource 2. The orthogonal grids for backwardfacing step flow are generated, they are illustrated in fig. Cfd simulation of backward facing step this tutorial is a wellknown academic problem that one should solve while learning cfd. The dynamics of the transitional flow over a backwardfacing step. Turbulent flow over a backwardfacing step is studied by direct numerical solution of the navierstokes equations. Backwardfacing step flows for various expansion ratios at. The finite volume method was used to solve the corresponding continuity, momentum, and energy equations using the. In this paper, the flow configuration was the same as the one used in a previous study, as shown in figure 1.
Flow over a backwardfacing step is a widely used benchmark case in the field of computational fluid dynamics cfd. Three cases, corresponding to three different step heights, were investigated for reynolds numbers ranging from 30,000 to 100,000 and temperatures ranging. Computational simulation of backward facing step flow using immersed boundary method. The internal flow over a backwardfacing step in the transitional regime red. The flow separation and recirculation caused by a sudden contraction in a channel, in the form of a forwardbackward facing step.
I am trying to repeat the results in a paper by gartling d. On simulation of backward facing step flow using immersed boundary method. Numerical investigation of fluid flow through a 2d backward. This code was created as a final project for a cfd course. The tutorial will cover simulation steps and post processing required to solve steady state, turbulent flow over backward facing step problem using ansys fluent software. The flow separation is caused due to the sudden changes in the geometry.
Large eddy simulation of flow over a backward facing step. The predictions were carried out with the help of a finitevolume navierstokes solver equipped with a covisualization facility which allows one to investigate the flow dynamics at high temporal resolution. Simulation of turbulent flow over a backwardfacing step at re9000. In this project, the flow over a backward facing step is simulated with icofoam solver on openfoam. The 2d incompressible navierstokes equations was solved in generalized curvilinear coordinates using arti cial compressibility method. The research in such a flow was escalated with the experimental and numerical work of armaly et al. Numerical simulation software has evolved far beyond what navier, stokes or da. Another kind of flow is the flow over steps, such as the flow over a backwardfacing step as investigated by le et al. The aim of this test case is to validate steadystate flow over a backwardfacing step. We have decided to simulate flow through a backward facing step to study the flow of fluids through geometries that have suddenchanging shapes. Flow over a backward facing step with parabolic velocity profile at inlet. Large eddy simulation of rearwardfacing step flow aiaa.
It simulates a steady 2d flow over a backward facing step. The flow separation and recirculation caused by a sudden contraction in a channel, in the form of a forward backward facing step is an example for the same. Backward facing step is chosen for its apparent geometrical simplicity, but it involves relatively complex flow phenomena. Solution domain the domain is 2 dimensional, consisting of a short inlet, a backwardfacing step and converging nozzle at outlet as shown in figure 3. Large eddy simulation of backward facing step flow balram panjwani email. Simulation of backward facing step flow using openfoam. Turbulent flow over a backwardfacing step cfd autodesk. Simulation of steady, laminar flow over a backward facing step sagar bhatt masters student department of mechanical and aerospace engineering, university at bu alo. One of the difficulties in the numerical simulation of backward facing step is that the region of circulation is highly. The step expansion ratio12 and the ow at the step was assumed to be fully developed, laminar channel ow.
On the flow characteristics behind a backwardfacing step. The heated turbulent flow over a backwardfacing step is numerically solved using the commercial computational fluid dynamics program fluent. The computational domain was 35 h in the streamwise direction, 2. Commercial software package ansys fluent has been used for the numeric simulation. By simulating the flow over a backwardfacing step and analyzing the instability of fluid in different blowing and suction cases, the mechanism of structural damages and the principle of vortex shedding were studied.
Ansys fluent 14 cfd software was employed to run the simulations. Cfd simulation of heat transfer and turbulent fluid flow over a. Backwardfacing step simulation cfd online discussion. The grids are refined at the corner and at the boundary layer region. Cfd simulation using fluent and rans3d 1 avalidation exercise 1. Simulating flow through backward facing step using. The present thesis deals with the code development of a 2d finite volume and. To run this test case, follow these steps at a terminal command line. Cfd simulation of backward facing step projects skilllync. Flow over a backwardfacing step bfs is a common phenomenon in. Solutions of turbulent backwardfacing step flow with heat. Piv measurements in square backwardfacing step 21 february 2007 journal of fluids engineering, vol. The main objective of the present work is the comparison of different models of turbulence applied to the turbulent flow over a backwardfacing step. The simulation was conducted at a reynolds number of 5100 based on the step.
The topic under investigation is a very important one as flow over a backward facing step forms the basis of many real flow. The backwardfacing step is another common test case for cfd codes. The poissonboltzmann and navierstokes equations were computed by the highorder scheme, and the results confirmed the ability of the new solver in simulation of. To analyse and plot velocity, pressure contours and understand how flow seperation takes place. Pdf direct numerical simulation of turbulent flow over a. Forward backward facing step flows the study of flow separation is an important issue in fluid dynamics, which results in a total change of the flow field. Both groups concentrated on the flow field, transition mechanisms and turbulent statistics. Backward facing step bfs is widely known for its application in the studies on turbulence in internal flows. Computational simulation of backward facing step flow. This tutorial is based on cfd modeling software ansys fluent and will cover simulation steps and post processing required to solve steady state, turbulent flow. Numerical simulation and stability analysis of flow over a. Numerical simulation of a backwardfacing step flow in a. Pdf computational simulation of backward facing step flow.
Literature is extensive, with contributions from experimental, theoretical and computational fluid dynamics. During the simulation, it seems that the velocity blows up after a certain time. Orthogonal grids for the domain of backwardfacing step flow. This paper presents the numerical simulation of backwardfacing step using fire dynamics simulator fds, open source software. Direct numerical simulation of flow over a forwardfacing. In some numerical simulations the backward facing step flow problem is a benchmark for validating the computational simulation algorithm. The dynamics of the transitional flow over a backward. Tutorial cfd simulation of backward facing step learncax. In this paper fluid flow through a backward facing step has been studied numerically for a 2d channel having an expansion ration hh 2. Flow separation is one classic topic in fluid dynamics, which has become one key topic in external flows and is closely related to aerodynamic design of vehicles, mechanics and other moving bodies. Pdf simulation of backward facing step flow using openfoam. Simulating flow through backward facing step skilllync. Ansys has combined a number of engineering analysis software, such as ansysmechanical, ansysmeshing, and the computeraided design.
The backward facing step is an interesting case for studying the performance and solution strategy of a turbulence model. This tutorial is a wellknown academic problem that one should solve while learning cfd. The backwardfacing step simulation will execute relatively quickly on a single workstation or laptop in serial. Numerical investigation of fluid flow through a 2d. Analysis characteristics steadystate 2d internal, separated flow turbulent incompressible reference vogel, j. The incompressible, turbulent case is validated with the experimental results of driver and seegmiller as archived in the nasa turbulence modeling resource. Solution domain the domain is 2 dimensional, consisting of a short inlet, a backward facing step and converging nozzle at outlet as shown in figure 3. I am trying to perform a well known simulation of a 2d laminar steady state re 389 flow over a backwardfacingstep. Comparison of turbulence models in the flow over a. Flow over a backward facing step has been one of important research field in fluid mechanics. The simulation is carried for three different base mesh 2e3, 1. How to achieve a cfd flow over a backward facing step with parabolic velocity profile at inflow simulation. A grid of 71921600 grids see figure 12, in the x,y and z directions is used in the simulation. Fluid flow over a backward or forwardfacing step generates recirculation zones.
This present project comprises the simulation of the backwardfacing step using converge cfd software. The data is validated by comparison with existing experimental and numerical results. Backwardfacing step bfs has also been partially discussed in general previous studies of flow separation dynamics. But both of them will divergent after some time steps and break down. Turbulent flow over a backward facing step is studied by direct numerical solution of the navierstokes equations. Largeeddy simulation of particleladen turbulent flows. On simulation of backward facing step flow using immersed.