Workshop 6 Modeling of Catalytic Convertor Introductory FLUENT

WS 6: Catalytic Converter Introduction Workshop Supplement • A workshop to demonstrate how to

WS 6: Catalytic Converter Starting Fluent in Workbench Workshop Supplement 1. Open the Workbench

WS 6: Catalytic Converter Import Mesh Workshop Supplement This starts a new Fluent session

WS 6: Catalytic Converter Setting up the Models 1. 2. Workshop Supplement Select Pressure

WS 6: Catalytic Converter Materials Workshop Supplement Define the materials. Problem Setup > Materials

WS 6: Catalytic Converter Fluid Zone Conditions Workshop Supplement • Under Problem Setup >Cell

WS 6: Catalytic Converter Fluid Zone Conditions (2) Workshop Supplement • Under Problem Setup

WS 6: Catalytic Converter Operating Conditions Workshop Supplement • Under Problem Setup >Cell Zone

WS 6: Catalytic Converter Boundary Conditions Workshop Supplement Under Problem Setup > Boundary Conditions

WS 6: Catalytic Converter Boundary Conditions (2) Workshop Supplement Under Problem Setup > Boundary

WS 6: Catalytic Converter Boundary Conditions (3) Workshop Supplement Under Problem Setup > Boundary

WS 6: Catalytic Converter Solution Methods Workshop Supplement Under Problem Setup > Solution Methods

WS 6: Catalytic Converter Solution Controls Workshop Supplement Under Problem Setup > Solution Controls

WS 6: Catalytic Converter Residual Monitors Workshop Supplement Residual Monitoring Solution > Monitors 1.

WS 6: Catalytic Converter Surface Monitors Workshop Supplement Monitor points are used to monitor

WS 6: Catalytic Converter Initialization Workshop Supplement Before starting the calculations we must initialize

WS 6: Catalytic Converter First Order Solution Workshop Supplement • The solution process can

WS 6: Catalytic Converter Higher Order Solution Workshop Supplement • Under Solution>Solution Methods setup

WS 6: Catalytic Converter Convergence history of the solution • Workshop Supplement Convergence history

WS 6: Catalytic Converter Write Case/Data File Workshop Supplement You can now save the

WS 6: Catalytic Converter Post Processing • Workshop Supplement To Draw Contours of Static

WS 6: Catalytic Converter Post Processing • Workshop Supplement To get the pressure drop

WS 6: Catalytic Converter Post Processing Workshop Supplement • You can postprocess any results

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WS 6: Catalytic Converter Introduction Workshop Supplement • A workshop to demonstrate how to model porous media in FLUENT • Workshop models a catalytic convertor. Nitrogen flows in though inlet with an uniform velocity 22. 6 m/s, passes through a ceramic monolith substrate with square shaped channels, and then exits through the outlet. • Substrate is impermeable in Y and Z directions, which is modeled by specifying loss coefficients 3 order higher than in X direction ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -2 Ceramic Monolith Substrate Inlet Outlet April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Starting Fluent in Workbench Workshop Supplement 1. Open the Workbench (Start > Programs > ANSYS 12. 0 > ANSYS Workbench) 2. Drag FLUENT into the project schematic 3. Change the name to Catalytic 4. Double click on Setup 5. Choose 3 D and Double Precision under Options and retain the other default settings ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -3 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Import Mesh Workshop Supplement This starts a new Fluent session and the first step is to import the mesh that has already been created: 1. Under the File menu select Import> Mesh 2. Select the file catalytic_converter_125 k. msh. gz and click OK to import the mesh 3. After reading the mesh, check the grid using Mesh>Check option or by using Check under Problem Setup>General ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -4 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Setting up the Models 1. 2. Workshop Supplement Select Pressure Based, Steady state solver Problem Setup>General>Solver Specify Turbulence model Problem Setup > Models > Viscous Double click and select k-epsilon (2 eqn) under Model and Realizable under kepsilon model and retain the default settings for the other parameters 3. Make sure that the Energy Equation is disabled Problem Setup > Models> Energy ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -5 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Materials Workshop Supplement Define the materials. Problem Setup > Materials 1. Click on air to open Create/Edit Materials panel 2. Click on FLUENT Database…> Select nitrogen(n 2) from the list > Copy 3. Click on Change/Create ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -6 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Fluid Zone Conditions Workshop Supplement • Under Problem Setup >Cell Zone >Double click on part-in under Zone – Select Material Name : nitrogen – Default values for other settings – Click to OK • Similarly, visit to part-out Zone and select the same settings as above ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -7 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Fluid Zone Conditions (2) Workshop Supplement • Under Problem Setup ->Cell Zone ->Double click on part-catalyst under Zone – – – Select Material Name : nitrogen Select and click on Porous Zone Under Direction-1 Vector, specify as: 1, 0, 0 Under Direction-2 Vector, specify as: 0, 1, 0 Specify as per GUI under Viscous Resistance and Inertia Resistance Default values under Power law Model and Porosity ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -8 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Operating Conditions Workshop Supplement • Under Problem Setup >Cell Zone Conditions (operating conditions are also in BC panel) Click on Operating Conditions… and set the Operating Pressure (Pascal) to 101325 pascal ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -9 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Boundary Conditions Workshop Supplement Under Problem Setup > Boundary Conditions 1. Select inlet under Zone and choose velocity-inlet from the drop down menu under Type 2. Now double click on inlet under Zone Input all the parameters in Momentum tab as shown below ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -10 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Boundary Conditions (2) Workshop Supplement Under Problem Setup > Boundary Conditions 1. Select outlet under Zone and choose pressure-outlet from the drop down menu under Type 2. Now double click on outlet under Zone Input all the parameters in Momentum tab as shown below ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -11 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Boundary Conditions (3) Workshop Supplement Under Problem Setup > Boundary Conditions 1. Wall type boundary condition for the Zone: wall-part-catalyst, wallpart-in and wall-part-out 2. Interior type of boundary condition for the rest ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -12 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Solution Methods Workshop Supplement Under Problem Setup > Solution Methods 1. Select Coupled under Pressure-Velocity Coupling 2. Select Green-Gauss Node Based under Gradient 3. Default under other options ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -13 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Solution Controls Workshop Supplement Under Problem Setup > Solution Controls 1. Use default settings ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -14 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Residual Monitors Workshop Supplement Residual Monitoring Solution > Monitors 1. Double click on Residuals (By default it is on) 2. Enable Plot under Options. 3. Specify Absolute Criteria for continuity: 1 e-4 ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -15 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Surface Monitors Workshop Supplement Monitor points are used to monitor quantities of interest during the solution. They should be used to help judge convergence. In this case you will monitor the Mass Flow Rate at outlet and Static Pressure at inlet. Solution > Monitors > Surface Monitors ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -16 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Initialization Workshop Supplement Before starting the calculations we must initialize the flow field in the entire domain Solution > Monitors > Solution Initialization 1. Initializing the flow field with near steady state conditions will result in faster convergence 2. Select Compute from: inlet 3. Click on Initialize to initialize the solution ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -17 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter First Order Solution Workshop Supplement • The solution process can be started in the following manner Solution >Run Calculation • Enter 100 for Number of Iterations and click on Calculate During the iteration process, the residuals and monitor plots will be shown in different windows. You will see that both monitors become flat at 100 iterations. However, this is a solution of first order discretization scheme. To get an accurate solution, we will use higher order discretization scheme for pressure and momentum equations and run further. ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -18 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Higher Order Solution Workshop Supplement • Under Solution>Solution Methods setup the parameters as shown below • • The solution process can be started in the following manner Solution >Run Calculation Enter 100 for Number of Iterations and click on Calculate ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -19 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Convergence history of the solution • Workshop Supplement Convergence history of the solution can be found from the plots Scaled Residuals Convergence history of Mass Flow Rate on outlet ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. Convergence history of Static Pressure on inlet WS 6 -20 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Write Case/Data File Workshop Supplement You can now save the project and proceed to write a case file for the solver: 1. To save the project, go to Project Page File>Save as 2. To write the case/data files, go to FLUENT session File>Export>Case and Data. . Case/Data File: catalytic_converter_second. cas. gz ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -21 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Post Processing • Workshop Supplement To Draw Contours of Static Pressure on walls Display > Graphics and Animations Double Click on Contours, a new window will pop up Select Pressure under Contours of and Static Pressure below that Select all walls under Surfaces ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -22 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Post Processing • Workshop Supplement To get the pressure drop between inlet to outlet boundaries using the porous media model Reports > Surface Integrals Select as per the GUI and click to Compute You will get the information below Hence, the pressure drop is around 734 pascal ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -23 April 28, 2009 Inventory #002601

WS 6: Catalytic Converter Post Processing Workshop Supplement • You can postprocess any results using the FLUENT postprocessing tools and/or CFD-Post. ANSYS, Inc. Proprietary © 2009 ANSYS, Inc. All rights reserved. WS 6 -24 April 28, 2009 Inventory #002601