Demo of FLUENT in Workbench

1. Demo of FLUENT in Workbench André Bakker April 24, 2009

2. Purpose of demo • Set up and solve a FLUENT system in Workbench, showing these steps: • Geometry import with parametric modifications, flow volume extraction, splitting for symmetry. • Set up and solve in FLUENT. • Review results in CFD-Post. • Show to methods to perform parametric analysis: • Using the duplicate option. • Using a design points table.

3. Example case • Perform parametric analysis showing performance as a function of inlet pipe length and velocity at the side inlet. • Static mixer geometry created in GAMBIT. • Exported as Parasolid file. • One main inlet, a side inlet, and an outlet. • The depth that the side inlet sticks into the main pipe will be parameterized in DM. • Will solve flow field and temperature field for two streams with different inlet temperature mixing. • Calculate mixing efficiency with expression language in CFD-Post.

4. Demonstration

5. Create fluid flow system • Start WB. • Create a FLUENT system named “Chemical Mixer”. • Geometry → import → mixer-sideinlet-inside.x_t. • Geometry → Edit.

6. Extrude side pipe (1/4) • Create → New Plane. • Details View → Type → From Face. • Click on Not selected.

7. Extrude side pipe (2/4) • Click on face at end of pipe. • Apply. • Generate.

8. Extrude side pipe (3/4) • Click Extrude icon. • Change FD1, Depth (>0) from 1m to 0.05m. • Click checkbox next to FD1. • Keep default parameter name.

9. Extrude side pipe (4/4) • Click Generate. • Exruded pipe is now generated.

10. Close inlets and outlet (1/2) • Use Concept → Surfaces from edges to close the inlet and outlet openings. • Select the three edges shown (hold ctrl key while selecting).

11. Close inlets and outlet (2/2) • Click apply and generate. • Three transparent faces are created as shown. • To extract flow volume: Tools → Fill.

12. Extract flow volume • Change Extraction Type from By Cavity to By Caps. • Click Generate. • Select new item Fill1 in tree Outline. • Highlights flow volume.

13. Split for symmetry (1/3) • To split geometry: Tools → Symmetry. • Select XYPlane in Tree Outline. • Click Apply, then Generate.

14. Split for symmetry (2/3) • In Tree Outline, expand “2 Parts, 2 Bodies”. • Right-click on Solid. • Rename this to Fluid.

15. Split for symmetry (3/3) • In Tree Outline, switch back and forth between Part 1 and Fluid (under “2 Parts, 2 Bodies) to show the solid part and the flow volume. • Close DM.

16. Show design point table • In WB, you can double click on the Parameter Set bar. The parameter setting the length of the inlet pipe will be shown. • Close the tables.

17. Meshing – suppress solid • In WB: Mesh → Edit. • In Outline, volume.1 is the solid part and fluid is the flow volume. • Select Part 1, right-click and Suppress body.

18. Named selection - Symmetry • Select the four symmetry surfaces, right click, Named Selection → name as “symmetry”.

19. Named selection - inlets • Name large inlet as “inlet-main” and small inlet as “inlet-side”. • Select the Named Selections in the Outline to highlight them.

20. Named selection - outlets • Name the outlet “outlet”.

21. Named selection – wall-pipe • Select the main pipe wall and name it “wall-pipe”.

22. Update mesh • Select Mesh in the Outline. • Expand Sizing. • Change Use Advanced Size Function to “On: Proximity and Curvature”. • Set Min Size to 0.01. • Click Update. • Expand Statistics. • Shows ~51k elements.

23. Display mesh section (1/2) • Click new Section Plane icon. • Draw a line on the screen.

24. Display mesh section (2/2) • Click the pyramid icon under Section Planes. • Move the blue slider box to change the position of the plane. • Click the dashed part of the line to switch sides. • Click the solid part of the line to just get the single plane. • Uncheck the Section Plane to get back to the regular view.

25. Launch FLUENT • Close Meshing. • In WB, right-click Setup cell, select Edit. • Opens FLUENT Launcher. • Click Ok to launch FLUENT.

26. FLUENT model setup • Models: Energy On. • Materials: change water to “Polygoopelyne”. Density 1100 kg/m3; Cp 4000 j/kg-k; Thermal conductivity 0.5 w/m-k; viscosity 1 kg/m-s. • Inlet-main: 0.1 m/s; thermal: temperature 300K. • Inlet-side: 0.1 m/s; thermal: temperature 350K.

27. FLUENT – output parameter • Boundary Conditions → Click Parameters • Create → Surface Integrals. • Area Weighted Average → inlet-side → Static Pressure. • Save Output Parameter → Name = pressure-side-inlet → OK → Close.

28. FLUENT - calculation • Run calculation: 70 iterations. • Calculate (may have to click Calculate button twice). • Close FLUENT. • To see the Table of Design Points: • Double click Parameter Set. • View → Table. • Update project to fill in the value for the pressure inlet parameter.

29. CFD-Post - Contour • In WB, right click on Results. Edit. • This opens CFD-Post. • Insert a contour: • Locations: inlet-main, inlet-side, outlet, symmetry, wall-fluid. • Variable: Static temperature. • # of Contours: 20. • Apply.

30. Expressions • Insert two new expressions using CEL. • Average temperature at outlet: Tave Out = massFlowAve(Static Temperature)@outlet • Temperature standard deviation at outlet: Tstdout = sqrt( massFlowAve( (Static Temperature – Tave Out)^2)@outlet) • Right-click on Tstd Out under Expressions on Expressions tab and select “Use as Workbench Output Parameter” • Quit CFD-Post.

31. Save project • Save the project. • In WB File → Save as → chemical-mixer.wbpj.

32. Duplicate system • Right-click on “Fluid Flow (FLUENT)”. • Click Duplicate. • Name the new system “Chemical Mixer – Long Inlet”.

33. Change inlet pipe length • Double click on Parameter Set. • View → Table. • Change the value of P3–Extrude1.FD1 to 0.1 (from 0.05). • Update Project. • Click Show Progress to show the progress during the calculation.

34. Update project • When the calculation is done (<2 minutes), show the design point table. • The pressure at the side inlet and the temperature standard deviation at the outlet are shown for the two different pipe lengths.

35. CFD-Post – load both result sets • Drag cell A5 (Solution) to cell B6 (Results). • Double-click cell B6 (Results) to open CFD-Post with both sets of results loaded.

36. CFD-Post – case comparison • Double click Case Comparison. • Check Case Comparison Active. • Check Use absolute value of differences. • Quit CFD-Post.

37. Save project • In WB → File → Save As → chemical-mixer-2-calculations.wbpj.

38. Optional – design point analysis • Optional demo. Create a table with design points for the system using input parameters to FLUENT and output parameters calculated with CFD-Post. • Starting point: the system saved as “chemical-mixer.wbpj”. • In WB: File →“chemical-mixer.wbpj”.

39. Input parameter in FLUENT • Setup → Edit • Boundary condition: inlet-side • Velocity Magnitude; new input parameter. Name: velocity-side. Current value 0.1 m/s. • Close FLUENT.

40. Add design points • Add additional design points as shown in the screenshot. • Note: to save the results for each design point, check the checkbox in the Exported column.

41. Solve Parametric Analysis (2) • Right-click on Solution cell A5 and select Clear Generated Data (may not be necessary in release version). • Click on “Update All Design Points” button from toolbar. • Workbench solves all design points sequentially. • Output parameter values* are displayed in the Table of Design Points as each run is completed.

42. Save project • In WB → File → Save As → chemical-mixer-five-calculations.wbpj • Demonstration is complete.