Simulation of Laminar Pipe Flows57:020 Mechanics of Fluids and Transport ProcessesCFD PRELAB 1Simulation of Laminar Pipe Flows 57:020 Mechanics of Fluids and Transport Processes CFD PRELAB 1 By Timur Dogan, Michael Conger, Maysam Mousaviraad, Tao Xing and Fred Stern IIHR-Hydroscience & Engineering The University of Iowa C. Maxwell Stanley Hydraulics Laboratory Iowa City, IA 52242-1585 1. Purpose The Purpose of CFD PreLab 1 is to teach students how to use the CFD educational interface (ANSYS), be familiar with the options in each step of CFD Process, and relate simulation results to AFD concepts. Students will simulate laminar pipe flow following the “CFD process” by an interactive step-by-step approach. Students will have “hands-on” experiences using ANSYS to compute axial velocity profile, centerline velocity, centerline pressure, and wall shear stress. Students will compare simulation results with AFD data, analyze the differences and possible numerical errors, and present results in CFD Lab 1 report. Flow chart for “CFD Process” for pipe flow Geometry Physics Mesh Solution Results Pipe (ANSYS Design Modeler) Structure (ANSYS Mesh) Non-uniform (ANSYS Mesh) Uniform (ANSYS Mesh) General (ANSYS Fluent - Setup) Model (ANSYS Fluent - Setup) Boundary Conditions (ANSYS Fluent -Setup) Reference Values (ANSYS Fluent - Setup) Laminar Turbulent Solution Methods (ANSYS Fluent - Solution) Monitors (ANSYS Fluent - Solution) Solution Initialization (ANSYS Fluent -Solution) Plots (ANSYS Fluent- Results) Graphics and Animations (ANSYS Fluent- Results) 12. Simulation Design In EFD Lab 2, you conducted experimental study for turbulent pipe flow. The data you have measured will be used for CFD Lab 1. In CFD PreLab 1, simulation will be conducted only for laminar circular pipe flows, i.e. the Reynolds number is less than 2300. Reynolds number based on pipe diameter and mean inlet velocity is 654.75 in the current simulation. CFD predictions of friction factor and fully developed axial velocity profile will be compared with AFD data. Table 1 – Geometry dimensions Parameter Unit Value Radius of Pipe m 0.02619 Diameter of Pipe m 0.05238 Length of the Pipe m 7.62 Since the flow is axisymmetric we only need to solve the flow in a single plane from the centerline to the pipe wall. Boundary conditions need to be specified include inlet, outlet, wall, and axis, as will be described in details later. Uniform flow is specified at inlet, the flow will reach the fully developed regions after a certain distance downstream. No-slip boundary condition will be used on the wall and constant pressure for the outlet. Symmetric boundary condition will be applied on the pipe axis. Since the flow is laminar, turbulence models are not necessary. Navigation Tips • To zoom in and out use the magnifying glass with a plus sign in it and drag, from top left to bottom right over the are you wish to zoom. • To look at a view plane, simply click on the arrow in the coordinate system identifier in the bottom right of the screen. i.e if you wish to look at the XYplane, click on the Z Arrow. Outlet Inlet Symmetry Pipe Wall Non-uniform mesh Uniform mesh Velocity Profile Figure 1 - Geometry 23. Open ANSYS Workbench 3.1. Start > All Programs > ANSYS 14.5 > Workbench 14.5 3.2. From the ANSYS Workbench home screen (Project Schematic), drag and drop the Geometry component for the Component Systems on the left side of the screen into the Project Schematic. Rename the geometry by right clicking on the down arrow of the Geometry component and selecting Rename. 33.3. Drag and drop two Mesh components and two Fluent components into the schematic as shown below. Rename the components as you did the geometry previously as per the as shown below. Make the connections as per below by dragging component to component. 3.4. Create a Folder on the H: Drive called CFD Pre-Lab and Lab 1. 3.5. Save the project file by clicking File > Save As… 3.6. Save the project onto the H: Drive in the folder you just created and name it CFD Pre-Lab and Lab 1 Pipe Flow. (This will be used for both Pre-Lab 1 and Lab 1.) 4. Geometry Creation 4.1. Right click on Geometry and from the drop down menu select New Geometry… 4.2. Select Meter for unit and click OK. 44.3. Select the XYPlane under the Tree Outline and click New Sketch button. 4.4. Right click XYPlane and select Look at. 4.5. Select Sketching > Rectangle. Create a rectangle geometry as per below, make sure to start from the origin, the mouse arrow should change to a “P” when on the origin. 54.6. Select Dimensions > General. Click on top edge then click above the geometry to place the dimension. Repeat the same thing for one of the vertical edges. You should have a similar figure as per below. 4.7. Click on H1under Details View, in the bottom left of the screen, and change H1 to 7.62m. Click on V2 and change it to 0.02619m. 4.8. Concept > Surface From Sketches, select the sketch by clicking on Sketch 1 in the Tree Outline and hit Apply in the Detatils View. 64.9. Click Generate. This will create a surface. 4.10. File >Save Project. Save project and close the Design Modeler window. 5. Mesh Generation 5.1. From the Project Schematic right click on Mesh on the Fluid Flow (Fluent) component and select Edit… 5.2. Right click on Mesh then select Insert > Mapped Face Meshing. 75.3. Select your geometry by clicking the yellow box which says No Selection, the click on the geometry surface, and click Apply. 5.4. Click on the edge button. This will allow you to select edges of your geometry. 85.5. Right click on Mesh then select Insert > Sizing. 5.6. Hold Ctrl button and select the top and bottom edge of the rectangle then click Apply. Specify details of sizing as per below in the Details of “Edge Sizing” – Sizing window. 5.7. Repeat step 5.5. Select the left and right edge of the rectangle and click Apply then change sizing parameters as per below. 95.8. Click on Generate Mesh button. Click Mesh under Outline. The mesh should look like the mesh pictured below. 5.9. Change the edge names by selecting the edge, then right clicking on the edge and selecting Create Named Selection. Name left, right, bottom and top edges as inlet, outlet, axis and wall respectively. Your outline should look same as the figure below. Uniform Mesh 105.10. File
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