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ii. Enter the values in Table 7.2 for the Viscous Resistance and Inertial Resistance. Scroll down to access the fields that are not initially visible in the panel.

(e) Click OK to close the Fluid panel.

3. Set the velocity and turbulence boundary conditions at the inlet (inlet).

(a) Enter 22.6 m/s for the Velocity Magnitude.

(b) Select Intensity and Hydraulic Diameter from the Specification Method dropdown list in the Turbulence group box.

(c) Retain the default value of 10% for the Turbulent Intensity. (d) Enter 42 mm for the Hydraulic Diameter. (e) Click OK to close the Velocity Inlet panel.

4. Set the boundary conditions at the outlet (outlet).

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(a) Retain the default setting of 0 for Gauge Pressure.

(b) Select Intensity and Hydraulic Diameter from the Specification Method dropdown list in the Turbulence group box.

(c) Enter 5% for the Backflow Turbulent Intensity. (d) Enter 42 mm for the Backflow Hydraulic Diameter. (e) Click OK to close the Pressure Outlet panel.

5. Retain the default boundary conditions for the walls (substrate-wall and wall) and close the Boundary Conditions panel.

Step 5: Solution

1. Set the solution parameters. Solve /Controls /Solution...

(a) Retain the default settings for Under-Relaxation Factors.

(b) Select Second Order Upwind from the Momentum drop-down list in the Discretization group box.

(c) Click OK to close the Solution Controls panel.

2. Enable the plotting of residuals during the calculation. Solve/Monitors /Residual...

(a) Enable Plot in the Options group box.

(b) Click OK to close the Residual Monitors panel.

3. Enable the plotting of the mass flow rate at the outlet. Solve / Monitors /Surface...

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(a) Set the Surface Monitors to 1.

(b) Enable the Plot and Write options for monitor-1, and click the Define... button to open the Define Surface Monitor panel.

i. Select Mass Flow Rate from the Report Type drop-down list. ii. Select outlet from the Surfaces selection list.

iii. Click OK to close the Define Surface Monitors panel. (c) Click OK to close the Surface Monitors panel.

4. Initialize the solution from the inlet. Solve /Initialize /Initialize...

(a) Select inlet from the Compute From drop-down list. (b) Click Init and close the Solution Initialization panel.

5. Save the case file (catalytic converter.cas). File /Write /Case... 6. Run the calculation by requesting 100 iterations. Solve /Iterate...

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(a) Enter 100 for the Number of Iterations. (b) Click Iterate.

The FLUENT calculation will converge in approximately 70 iterations. By this point the mass flow rate monitor has attended out, as seen in Figure 7.3. (c) Close the Iterate panel.

7. Save the case and data files (catalytic converter.cas and catalytic converter.dat). File /Write /Case & Data...

Note: If you choose a file name that already exists in the current folder, FLUENT will prompt you for confirmation to overwrite the file.

Step 6: Post-processing

1. Create a surface passing through the centerline for post-processing purposes. Surface/Iso-Surface...

(a) Select Grid... and Y-Coordinate from the Surface of Constant drop-down lists. (b) Click Compute to calculate the Min and Max values. (c) Retain the default value of 0 for the Iso-Values.

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