Revision for “EP-706 ANSYS FLUENT Venturi Simulation Procedure” created on November 30, 2015 @ 19:28:57
| Title | EP-706 ANSYS FLUENT Venturi Simulation Procedure |
|---|---|
| Content | Date: <strong>July 15, 2015</strong>
<h1><strong>1. </strong><strong>PURPOSE</strong><strong> / DESCRIPTION</strong></h1>
<ul>
<li>To set a procedure to setup Venturi Effect testing on a sphere and a slanted cylinder in ANSYS Workbench
<ul>
<li>This follows the testing of a slanted cylinder in a 1 mm thick wall.</li>
</ul>
</li>
</ul>
<h1><strong>2. </strong><strong>Design Modeler (Sphere)</strong></h1>
<ul>
<li>Open a new project in Workbench</li>
<li>Place a Fluent analysis system and DCLK on the Geometry cell to open Design Modeler</li>
</ul>
<a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-01.png"><img class="wp-image-377 alignnone" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-01.png" alt="706-01" width="398" height="218" /></a>
<ul>
<li>Create > Primitives > Cylinder</li>
</ul>
<img class=" wp-image-378 alignnone" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-02.png" alt="706-02" width="311" height="212" /><img class="alignnone wp-image-379" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-03.png" alt="706-03" width="287" height="212" />
Generate (F5)
<ul>
<li>Create > Primitives > Box</li>
</ul>
<img class="alignnone wp-image-380" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-04.png" alt="706-04" width="305" height="208" /><img class="alignnone wp-image-381" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-05.png" alt="706-05" width="322" height="247" />
This will be the region where still air is. Decide appropriate dimensions depending on the simulation.
Generate (F5)
<ul>
<li>Create > Primitives > Box</li>
</ul>
<img class="alignnone wp-image-382" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-06.png" alt="706-06" width="310" height="212" /> <a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-07.png"><img class="alignnone wp-image-383" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-07.png" alt="706-07" width="282" height="219" /></a>
This will be the region where the air flows.
Generate (F5)
<ul>
<li>Create > Body Transformation > Rotate
<ul>
<li>Bodies = Select the cylinder (in the graphics window or Tree Outline)</li>
<li>Axis Selection = click on YZPlane in Tree Outline<a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-08.png"><img class="alignnone wp-image-384" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-08.png" alt="706-08" width="395" height="307" /></a></li>
<li>Make sure the arrow is in the right direction and click Apply</li>
<li>Angle = 45 (For this case)</li>
</ul>
</li>
<li>Create > Boolean
<ul>
<li>Operation = Unite</li>
<li>Tool Bodies = select all the primitives created</li>
<li>Generate (F5)</li>
</ul>
</li>
<li>Click on the newly created body in Tree Outline and change its Fluid/Solid to Fluid</li>
<li>Final result should look like this:<img class="wp-image-385 aligncenter" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-09.png" alt="706-09" width="458" height="345" /><img class="wp-image-386 aligncenter" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-10.png" alt="706-10" width="396" height="299" /></li>
</ul>
<ul>
<li>Close Design Modeler</li>
</ul>
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<h1><strong>3. </strong><strong>Meshing</strong></h1>
<ul>
<li>DCLK the Meshing cell to open up ANSYS Meshing</li>
<li>Units > Metric (mm, kg, N, s, mV, mA)</li>
<li>RCLK on Mesh in the Outline tree > Preview > Surface Mesh
<ul>
<li>Preview the surface mesh before generating the whole mesh when altering settings. A bad orthogonal quality in the surface mesh will end up bad as a whole mesh.</li>
</ul>
</li>
<li>Click on Mesh in the Outline tree</li>
</ul>
<table>
<tbody>
<tr>
<td rowspan="2" width="128">Defaults</td>
<td width="255">Physics Preference</td>
<td width="405">CFD</td>
</tr>
<tr>
<td width="255">Solver Preference</td>
<td width="405">Fluent</td>
</tr>
<tr>
<td rowspan="4" width="128">Sizing</td>
<td width="255">Use Advanced Sizing Function</td>
<td width="405">On: Proximity and Curvature</td>
</tr>
<tr>
<td width="255">Relevance Center</td>
<td width="405">Fine</td>
</tr>
<tr>
<td width="255">Span Angle Center</td>
<td width="405">Fine</td>
</tr>
<tr>
<td width="255">Curvature Normal Angle</td>
<td width="405">10°
(should be adjusted depending on geometry)</td>
</tr>
<tr>
<td width="128">Patch Conforming Options</td>
<td width="255">Triangle Surface Mesher</td>
<td width="405">Advancing Front</td>
</tr>
<tr>
<td width="128">Statistics</td>
<td width="255">Mesh Metric</td>
<td width="405">Orthogonal Quality
Use this to assess if the mesh is at an acceptable quality. You want your Min to be above than .40 for 2D surface mesh and above .05 for 3D.</td>
</tr>
</tbody>
</table>
<ul>
<li>Click on <a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/702-08.png"><img class="alignnone size-full wp-image-260" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/702-08.png" alt="702-08" width="29" height="20" /></a>and create a section plane along the YZ axis to better view the slanted hole.<img class="aligncenter wp-image-388" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-12.png" alt="706-12" width="627" height="476" /></li>
</ul>
<ul>
<li>Creating Named Selections
<ul>
<li>Select the face of the cylinder
<ul>
<li>RCLK on the graphics window > Create Named Selections</li>
<li>Name it “wall-hole”</li>
</ul>
</li>
</ul>
</li>
</ul>
<ul>
<li>Do the same for other faces as shown (this is taken from an example with a sphere as the hole to better view the surfaces):<img class="aligncenter wp-image-389" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-13.png" alt="706-13" width="650" height="481" /><img class="aligncenter wp-image-390" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-14.png" alt="706-14" width="651" height="469" /></li>
</ul>
<ul>
<li>Select all other faces that have not been named and name them “openings”</li>
<li>Select the whole body (not a face) and name it “air-volume”</li>
</ul>
<ul>
<li>RCLK on Mesh > Insert > Sizing
<ul>
<li>Select the whole body for Scope.<img class="wp-image-391 aligncenter" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-15.png" alt="706-15" width="468" height="355" /></li>
</ul>
</li>
</ul>
<img class="wp-image-480 aligncenter" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-unsequenced.png" alt="706-unsequenced" width="389" height="174" />
<ul>
<li>RCLK on Mesh > Generate Mesh</li>
<li>Click on <a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-unsequenced2.png"><img class="alignnone size-full wp-image-484" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-unsequenced2.png" alt="706-unsequenced2" width="74" height="23" /></a> <a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-16.png"><img class="wp-image-392 aligncenter" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-16.png" alt="706-16" width="639" height="476" /></a></li>
</ul>
<a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-17.png"><img class="wp-image-394 aligncenter" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-18.png" alt="706-18" width="297" height="360" /><img class="wp-image-393 aligncenter" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-17.png" alt="706-17" width="302" height="304" /></a>
<h1></h1>
<h1></h1>
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<h1><strong>4. </strong><strong>Fluent Setup & Solution</strong></h1>
<ul>
<li>DCLK on Setup cell in Workbench to open Fluent</li>
<li>Choose these options (use Serial for Processing Options if HPC license not available)<a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-19.png"><img class=" wp-image-395 aligncenter" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-19.png" alt="706-19" width="411" height="419" /></a></li>
</ul>
<strong>Setup</strong>
<ul>
<li>General
<ul>
<li>Click on Report Quality (Confirm that the values that appear are not close to the extremes that Fluent describes)</li>
<li>Click on Check</li>
</ul>
</li>
<li>Models
<ul>
<li>DCLK (double click) on Viscous
<ul>
<li>Model = k-omega (2 eqn)</li>
<li>k-omega Model = SST</li>
</ul>
</li>
<li>Boundary Conditions
<ul>
<li>DCLK on inlet</li>
</ul>
</li>
</ul>
</li>
</ul>
<table>
<tbody>
<tr>
<td rowspan="3" width="135">Momentum</td>
<td width="315">Velocity Specification Method</td>
<td width="339">Magnitude, Normal to Boundary</td>
</tr>
<tr>
<td width="315">Reference Frame</td>
<td width="339">Absolute</td>
</tr>
<tr>
<td width="315">X-Velocity (m/s)</td>
<td width="339">2.23519629494
This is 5 mph in m/s. Choose appropriate desired velocity.</td>
</tr>
</tbody>
</table>
<ul>
<li>DCLK on outlet</li>
</ul>
<table>
<tbody>
<tr>
<td width="135">Momentum</td>
<td width="315">Gauge Pressure (pascal)</td>
<td width="339">0</td>
</tr>
</tbody>
</table>
<ul>
<li><strong>Change the type of “openings” to pressure-inlet</strong></li>
</ul>
<strong>Solution</strong>
<ul>
<li>Solution Methods</li>
</ul>
<table>
<tbody>
<tr>
<td width="195">Pressure-Velocity Coupling</td>
<td width="315">Scheme</td>
<td width="339">COUPLED</td>
</tr>
<tr>
<td rowspan="5" width="195">Spatial Discretization</td>
<td width="315">Gradient</td>
<td width="339">Least Squares Cell Based</td>
</tr>
<tr>
<td width="315">Pressure</td>
<td width="339">Second Order</td>
</tr>
<tr>
<td width="315">Momentum</td>
<td width="339">Third-Order MUSCL
Second Order Upwind will work as well, but it may take longer to converge.</td>
</tr>
<tr>
<td width="315">Turbulent Kinetic Energy</td>
<td width="339">Third-Order MUSCL
Second Order Upwind will work as well, but it may take longer to converge.</td>
</tr>
<tr>
<td width="315">Specific Dissipation Rate</td>
<td width="339">Third-Order MUSCL
Second Order Upwind will work as well, but it may take longer to converge.</td>
</tr>
</tbody>
</table>
<ul>
<li>Refer to notes and course material to choose appropriate scheme and discretization methods.</li>
</ul>
<ul>
<li>Solution Controls
<ul>
<li>These values should be changed case by case, but the defaults seem to be sufficient for the procedure-specific example.</li>
<li>Decrease the Courant number and relaxation factors if the residuals are oscillatory. Decreasing them too much will lead to longer runtime.</li>
</ul>
</li>
<li>Solution Initialization
<ul>
<li>Click Initialize (while Hybrid Initialization is chosen)</li>
<li>Choose Standard Initialization</li>
</ul>
</li>
</ul>
<table>
<tbody>
<tr>
<td width="195"></td>
<td width="315">Compute from</td>
<td width="339">inlet</td>
</tr>
<tr>
<td width="195"></td>
<td width="315">Reference Frame</td>
<td width="339">Absolute</td>
</tr>
</tbody>
</table>
<ul>
<li>Click Initialize</li>
</ul>
<ul>
<li>Surface > Iso-Surface</li>
</ul>
<a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-22.png"><img class="wp-image-398 aligncenter" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-22.png" alt="706-22" width="548" height="341" /></a> <a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-21.png"><img class=" wp-image-397 aligncenter" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-21.png" alt="706-21" width="545" height="333" /></a>
<ul>
<li>This iso-surface is to measure volume flow across the cylinder. Notice that the Iso-Values is just above where the bottom hole is for the cylinder.</li>
</ul>
<ul>
<li>Surface > Iso-Surface</li>
</ul>
<a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-24.png"><img class="wp-image-400 aligncenter" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-24.png" alt="706-24" width="614" height="227" /></a> <a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-23.png"><img class="size-full wp-image-399 aligncenter" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-23.png" alt="706-23" width="507" height="408" /></a>
<ul>
<li>Monitors
<ul>
<li>Click on Create under Surface Monitors</li>
</ul>
</li>
</ul>
<table>
<tbody>
<tr>
<td width="135"></td>
<td width="315">Name</td>
<td width="339">vol-flow</td>
</tr>
<tr>
<td width="135"></td>
<td width="315">Report Type</td>
<td width="339">Volume Flow Rate</td>
</tr>
<tr>
<td rowspan="2" width="135">Options</td>
<td width="315">Print to Console</td>
<td width="339">checked</td>
</tr>
<tr>
<td width="315">Plot</td>
<td width="339">checked</td>
</tr>
<tr>
<td width="135"></td>
<td width="315">Surfaces</td>
<td width="339">hole</td>
</tr>
</tbody>
</table>
<ul>
<li>The pressure plot will be used to see that values are stabilizing while solving.</li>
</ul>
<ul>
<li>DCLK on Residuals
<ul>
<li>Change all the absolute criteria to 0.0001</li>
</ul>
</li>
<li>Click on Convergence Manager</li>
</ul>
<a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-24.png"><img class="alignnone wp-image-400" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-24.png" alt="706-24" width="662" height="245" /></a>
<ul>
<li>Calculation Activities
<ul>
<li>Autosave Every (Iterations) = 200 (can be changed to 0 or another value if needed)</li>
</ul>
</li>
<li>Run Calculation
<ul>
<li>Number of Iterations = 700
<ul>
<li>It is unlikely that the solver will meet the residual criteria because of one or two of the residuals showing slow decrease or oscillatory behavior. However, by this number of iterations, the solution should’ve stabilized enough.</li>
</ul>
</li>
<li>Click Check Case. There should be no recommendations that appear.</li>
<li>File > Save Project</li>
<li>Click Calculate</li>
<li>Click and choose an option to show all of the plots as the solver is solving. The window should show something similar to the screenshot below.</li>
</ul>
</li>
</ul>
<ul>
<li>Check on the residuals to see that they decrease monotonically and the other plots to see that they reach a steady value. In general, residuals should be below 1e-4 to confirm convergence. However, the matter of convergence is problem-dependent, so the other values, such as drag coefficient, need to be monitored in addition to the residuals. Small oscillations in the variables may occur due to the characteristics of the flow, and so identifying convergence will be subject to individual judgment.</li>
<li>If the solver is not converging it is a good idea to decrease the Courant number (you may or may not have this depending on the solver scheme) and relaxation factors bit by bit to help the solver converge.</li>
<li>File > Save Project</li>
</ul>
<h1><strong>5. </strong><strong>Setup & Solution PROCEDURE</strong></h1>
<strong>Results</strong>
<ul>
<li>Plots > DCLK on XY Plot</li>
</ul>
<table>
<tbody>
<tr>
<td width="348"></td>
<td width="229">Y Axis Function</td>
<td width="257">Turbulence…</td>
</tr>
<tr>
<td width="348"></td>
<td width="229"></td>
<td width="257">Wall Yplus</td>
</tr>
<tr>
<td rowspan="3" width="348">Plot Direction</td>
<td width="229">X</td>
<td width="257">1</td>
</tr>
<tr>
<td width="229">Y</td>
<td width="257">0</td>
</tr>
<tr>
<td width="229">Z</td>
<td width="257">0</td>
</tr>
<tr>
<td width="348"></td>
<td width="229">X Axis Function</td>
<td width="257">Direction Vector</td>
</tr>
<tr>
<td width="348"></td>
<td width="229">Surfaces</td>
<td width="257">wall-hole</td>
</tr>
</tbody>
</table>
<ul>
<li>Click Plot and a plot like the one below should show. Yplus is a dimenionless value that shows how far the first grid point is from a wall and is important to consider. Y-plus in this case is around .25 which is more than sufficient. Same criterion can be applied to different cases. You can either screenshot this or use the camera button.<a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-25.png"><img class="alignnone wp-image-401" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-25.png" alt="706-25" width="650" height="305" /></a></li>
</ul>
<ul>
<li>Reports > DCLK on Surface Integrals
<ul>
<li>Have hole selected in Surface.</li>
<li>Report Types to compute (you can save these as output parameters or write them):
<ul>
<li>Area</li>
<li>Volume Flow Rate</li>
<li>Mass Flow Rate</li>
</ul>
</li>
<li><strong>There are numerous analyses and graphics you can produce within Fluent. Search notes and researches for methods to obtain needed renderings and data.</strong></li>
<li>Graphics
<ul>
<li>Contours<a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-27.png"><img class="alignnone wp-image-403" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-27.png" alt="706-27" width="690" height="312" /></a> <a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-26.png"><img class="alignnone wp-image-402" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-26.png" alt="706-26" width="389" height="399" /></a></li>
<li>Vectors<a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-28.png"><img class="alignnone wp-image-405" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-29.png" alt="706-29" width="681" height="370" /><img class="alignnone wp-image-404" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-28.png" alt="706-28" width="401" height="455" /></a></li>
<li>Pathlines<a href="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-30.png"><img class="alignnone wp-image-407" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-31.png" alt="706-31" width="666" height="500" /><img class="alignnone wp-image-406" src="http://wiki.vairdo.com/wp-content/uploads/2015/11/706-30.png" alt="706-30" width="502" height="312" /></a></li>
</ul>
</li>
</ul>
</li>
</ul>
<ul>
<li>File > Export > Case & Data… > Save with appropriate name to represent this case.
<ul>
<li>This can be used to compare different cases later on.</li>
</ul>
</li>
<li><strong>Automation of running different cases and post-processing them can be found in ETP-</strong></li>
<li>Close ANSYS Fluent</li>
</ul> |
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