<p> CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Example on using commercial software “CFX 5.7.1”</p><p>Flow around a circular cylinder</p><p>Y.F.Lin</p><p>1 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Two Dimensional problems</p><p>Flow around a circular cylinder</p><p>After established the geometry model, we begin to use CFX to solve this two dimensional case.</p><p>Processing with CFX-5.7.1</p><p>1. Open CFX</p><p>Double click the “CFX” Icon , afterwards, you can see the interface of the CFX.</p><p>There are three kinds of functions of the CFX: 1. CFX-Pre 5.7.1 (set the relevant parameters). 2. CFX-Solver 5.7.1 (solve the case by using established physical model) 3. CFX-Post 5.7.1 (get the data and figures which we need)</p><p>CFX-Pre step: 1. Import the mesh file from ICEM CFD 2. Simulation type 3. Domain 4. BC’s (boundary conditions) 5. Initial conditions 6. Solver control 7. Output file and monitor points 8. Write “.def” file and simulation</p><p>2 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Click button “CFX-Pre 5.7.1” and run it.</p><p>E stablish a new simulation Open File>New Simulation…: </p><p>Select button “General” and give the file name with “cylinder_2d”. Click “Save”</p><p>3 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Now we can see the interface of the CFX-Pre</p><p>Import mesh file</p><p>See the middle position of the screen, Click button “Import mesh”</p><p>4 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Open Mesh>Definition>Mesh Format: From the pull down menu select “ICEM CFD”, (see figure below)</p><p>Definition>File: Click button “Browse”</p><p>Find the working direction and select the file named “cfx5”, Then click “Open” button. And “OK” Note: no other files can be inputted in CFX5.7.1 </p><p>5 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Then the mesh file has been inputted into the CFX-Pre</p><p>And the left window appears.</p><p>All of these names were already defined by us in “ICEM CFD” </p><p>Set the relevant parameters</p><p>1. Define the simulation type:</p><p>Click button “Define the Simulation Type” button.</p><p>6 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Note: the blue color note suggest we should set a domain.</p><p>Then the simulation type appears</p><p>Basic Settings>Option: Select “Transient” </p><p>7 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Basic Settings>Time Duration>Option: From the pull down menu select Total Time. Basic Settings>Time Duration>Total Time: Set with 42000s. Basic Settings>Time Steps>Option: From the pull down menu select Timesteps. Basic Settings>Time Steps>Timesteps: Set with 1s. Initial Time>Option: From the pull down menu select Autorratic. Then click Apply and Ok</p><p>2. Create a domain:</p><p>Click button “Create a Domain” .</p><p>Set the name with “ cylinder2d” and click Ok</p><p>8 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>See figure below: the color of the domain changed into green, and the window “Edit Domain” appears.</p><p>General Options>Basic Settings>Location: From the pull down menu select “FLUID2D” Then click “Apply” button</p><p>9 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Fluid Models>Heat Transfer Model>Option: Keep by default.</p><p>Fluid Models>Heat Transfer Model>Fluid Temperature: Set the temperature with 25c.</p><p>Fluid Models>Turbulence Model>Option: Set it with “None(Laminar). Click OK</p><p>3. Set boundary condtions:</p><p>Click button “Create a Boundary Condition”</p><p>Set INLET boundary condition</p><p>10 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Set the Name with “INLET” and click OK</p><p>11 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>12 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Basic Settings>Boundary Type: From the pull down menu select INLET.</p><p>Boundary Details>Flow Regime>Option: Select Subsonic.</p><p>Boundary Details>Mass And Momentum>Option: Select Normal Speed.</p><p>Boundary Details>Mass And Momentum>Normal Speed: Set it with 0.003 m/s</p><p>Click Ok</p><p>The right figure shows us that the INLET boundary condition has been set.</p><p>Set OUTLET boundary condition</p><p>13 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Set the Name with “OUTLET” and click OK</p><p>Basic Settings>Boundary Type: Outlet</p><p>Basic Settings>Location: From the pull down menu select OUTLET.</p><p>Boundary Details>Flow Regime>Option: Select Subsonic.</p><p>Boundary Details>Mass And Momentum>Option: Select Average Static Pressure.</p><p>Boundary Details>Mass And Momentum>Relative Pressure: Set with 0 Pa. </p><p>Boundary Details>Pressure Averaging>Option: Keep by default</p><p>Then click OK</p><p>14 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>15 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>The right figure shows us that the OUTLET boundary condition has been set.</p><p>Set Wall boundary conditions</p><p>Set the Name with “SIDEA” and click OK</p><p>16 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Basic Settings>Boundary Type: Wall.</p><p>Basic Settings>Location: From the pull down menu select SIDEA.</p><p>Boundary Details>Wall Influence On Flow>Option: Set with No Slip.</p><p>Then click Ok</p><p>17 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>The right figure shows us that the Wall boundary condition has been set (SIDEA).</p><p>The same way set SIDEB</p><p>18 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>The right figure shows us that the Wall boundary condition has been set.(SIDEB).</p><p>Set the CYLINDER with “Wall”</p><p>19 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Set the Name with “CYLINDER” and click OK</p><p>The right figure shows us that the Wall boundary condition has been set (CYLINDER).</p><p>Set “Fluid” and “Top” with symmetry boundary conditions</p><p>Set the Name with “SYM” and click OK</p><p>20 CFX Application – Computer Simulation of Flow around a circular cylinder</p><p>Basic Settings>Boundary Type: Symmetry.</p><p>Basic Settings>Location: Click button, then hold “Ctrl” button of the keyboard and use the left button of mouse to select FLUID and TOP. Click OK</p><p>Then Click Apply and Ok</p><p>The right figure shows us that the Symmetry boundary condition has been set (FLUID and TOP).</p><p>21</p>