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ANSYS CFX

Tutorials

ANSYS CFX Release 11.

December 2006

ANSYS, Inc. Southpointe

275 Technology Drive

Canonsburg, PA 15317 [email protected]

http://www.ansys.com (T) 724-746-

(F) 724-514-

ANSYS CFX Tutorials Page v

Table of Contents

Copyright and Trademark Information

Disclaimer Notice

U.S. Government Rights

Third-Party Software

Introduction to the ANSYS CFX Tutorials

Overview.............................................................................................. 1 Setting the Working Directory.......................................................................... 1 Changing the Display Colors............................................................................ 2

Tutorial 1: Simulating Flow in a Static Mixer Using CFX in Standalone Mode

Introduction........................................................................................... 3 Before You Begin....................................................................................... 4 Tutorial 1 Features..................................................................................... 4 Overview of the Problem to Solve....................................................................... 5 Defining a Simulation in ANSYS CFX-Pre................................................................ 6 Obtaining a Solution Using ANSYS CFX-Solver Manager................................................ Viewing the Results in ANSYS CFX-Post................................................................

Tutorial 1a: Simulating Flow in a Static Mixer Using Workbench

Introduction.......................................................................................... Before You Begin...................................................................................... Tutorial 1a Features...................................................................................

Table of Contents: Tutorial 6: Buoyant Flow in a Partitioned Cavity

ANSYS CFX Tutorials Page vii

Obtaining a Solution Using ANSYS CFX-Solver Manager.............................................. 116 Viewing the Results in ANSYS CFX-Post.............................................................. 119

Tutorial 6: Buoyant Flow in a Partitioned Cavity

Introduction........................................................................................ 127 Tutorial 6 Features.................................................................................. 128 Overview of the Problem to Solve.................................................................... 128 Defining a Simulation in ANSYS CFX-Pre............................................................. 129 Obtaining a Solution using ANSYS CFX-Solver Manager.............................................. 134 Viewing the Results in ANSYS CFX-Post.............................................................. 135

Tutorial 7: Free Surface Flow Over a Bump

Introduction........................................................................................ 139 Tutorial 7 Features.................................................................................. 139 Overview of the Problem to Solve.................................................................... 140 Defining a Simulation in ANSYS CFX-Pre............................................................. 141 Obtaining a Solution using ANSYS CFX-Solver Manager.............................................. 148 Viewing the Results in ANSYS CFX-Post.............................................................. 149 Using a Supercritical Outlet Condition............................................................... 154

Tutorial 8: Supersonic Flow Over a Wing

Introduction........................................................................................ 155 Tutorial 8 Features.................................................................................. 155 Overview of the Problem to Solve.................................................................... 157 Defining a Simulation in ANSYS CFX-Pre............................................................. 157 Obtaining a Solution using ANSYS CFX-Solver Manager.............................................. 162 Viewing the Results in ANSYS CFX-Post.............................................................. 162

Tutorial 9: Flow Through a Butterfly Valve

Introduction........................................................................................ 165 Tutorial 9 Features.................................................................................. 165 Overview of the Problem to Solve.................................................................... 166 Defining a Simulation in ANSYS CFX-Pre............................................................. 167 Obtaining a Solution using ANSYS CFX-Solver Manager.............................................. 180 Viewing the Results in ANSYS CFX-Post.............................................................. 180

Tutorial 10:

Table of Contents: Tutorial 11: Non-Newtonian Fluid Flow in an Annulus

Page viii ANSYS CFX Tutorials

Flow in a Catalytic Converter

Introduction........................................................................................ 185 Tutorial 10 Features................................................................................. 185 Overview of the Problem to Solve.................................................................... 186 Defining a Simulation in ANSYS CFX-Pre............................................................. 187 Obtaining a Solution using ANSYS CFX-Solver Manager.............................................. 193 Viewing the Results in ANSYS CFX-Post.............................................................. 194

Tutorial 11: Non-Newtonian Fluid Flow in an Annulus

Introduction........................................................................................ 199 Tutorial 11 Features................................................................................. 200 Overview of the Problem to Solve.................................................................... 201 Defining a Simulation in ANSYS CFX-Pre............................................................. 201 Obtaining a Solution using ANSYS CFX-Solver Manager.............................................. 205 Viewing the Results in ANSYS CFX-Post.............................................................. 206

Tutorial 12: Flow in an Axial Rotor/Stator

Introduction........................................................................................ 207 Tutorial 12 Features................................................................................. 208 Overview of the Problem to Solve.................................................................... 209 Defining a Frozen Rotor Simulation in ANSYS CFX-Pre................................................ 210 Obtaining a Solution to the Frozen Rotor Model...................................................... 214 Viewing the Frozen Rotor Results in ANSYS CFX-Post................................................. 215 Setting up a Transient Rotor-Stator Calculation....................................................... 216 Obtaining a Solution to the Transient Rotor-Stator Model............................................. 219 Viewing the Transient Rotor-Stator Results in ANSYS CFX-Post........................................ 220

Tutorial 13: Reacting Flow in a Mixing Tube

Introduction........................................................................................ 223 Tutorial 13 Features................................................................................. 223 Overview of the Problem to Solve.................................................................... 224 Outline of the Process............................................................................... 224 Defining a Simulation in ANSYS CFX-Pre............................................................. 225 Obtaining a Solution using ANSYS CFX-Solver Manager.............................................. 237 Viewing the Results in ANSYS CFX-Post.............................................................. 237

Tutorial 14:

Table of Contents: Tutorial 19: Cavitation Around a Hydrofoil

Tutorial 19:

Tutorial 20:

Tutorial 21:

Table of Contents: Tutorial 23: Aerodynamic & Structural Performance of a Centrifugal Compressor ANSYS CFX Tutorials Page xi Tutorial 23:

• Tutorial 18 Features Page x ANSYS CFX Tutorials
• Overview of the Problem to Solve.
• Using Eddy Dissipation and P1 Models
• Defining a Simulation in ANSYS CFX-Pre
• Obtaining a Solution using ANSYS CFX-Solver Manager
• Viewing the Results in ANSYS CFX-Post
• Laminar Flamelet and Discrete Transfer Models
• Further Postprocessing
• Introduction Cavitation Around a Hydrofoil
• Tutorial 19 Features
• Overview of the Problem to Solve.
• Creating an Initial Simulation
• Obtaining an Initial Solution using ANSYS CFX-Solver Manager
• Viewing the Results of the Initial Simulation
• Preparing a Simulation with Cavitation.
• Obtaining a Cavitation Solution using ANSYS CFX-Solver Manager
• Viewing the Results of the Cavitation Simulation
• Introduction Fluid Structure Interaction and Mesh Deformation
• Tutorial 20 Features
• Overview of the Problem to Solve.
• Using CEL Expressions to Govern Mesh Deformation
• Using a Junction Box Routine to Govern Mesh Deformation
• Introduction Oscillating Plate with Two-Way Fluid-Structure Interaction
• Tutorial 21 Features
• Overview of the Problem to Solve.
• Setting up the Solid Physics in Simulation (ANSYS Workbench)
• Setting up the Fluid Physics and ANSYS Multi-field Settings in ANSYS CFX-Pre.
• Obtaining a Solution using ANSYS CFX-Solver Manager
• Viewing Results in ANSYS CFX-Post
• Introduction Optimizing Flow in a Static Mixer
• Tutorial 22 Features
• Overview of the Problem to Solve.
• Creating the Project
• Creating the Geometry
• Creating the Mesh.
• Overview of ANSYS CFX-Pre
• Setting the Output Parameter in ANSYS CFX-Post
• Running Design Studies in DesignXplorer
• Introduction Aerodynamic & Structural Performance of a Centrifugal Compressor
• Tutorial 23 Features
• Overview of the Problem to Solve.
• Reviewing the Centrifugal Compressor Design
• Creating the Mesh in ANSYS TurboGrid
• Defining the Aerodynamic Simulation in ANSYS CFX-Pre
• Obtaining a Solution using ANSYS CFX-Solver Manager
• Viewing the Results in ANSYS CFX-Post
• Importing Geometry into DesignModeler
• Simulating Structural Stresses Due to Pressure Loads
• Simulating Structural Stresses Due to Rotation

ANSYS CFX Release 11.0. © 1996-2006 ANSYS Europe, Ltd. All rights reserved. Page 1 Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

ANSYS CFX Tutorials

Introduction to the

ANSYS CFX Tutorials

Overview

These tutorials are designed to introduce general techniques used in ANSYS CFX and provide tips on advanced modeling. Earlier tutorials introduce general principles used in ANSYS CFX, including setting up the physical models, running ANSYS CFX-Solver and visualizing the results. The remaining tutorials highlight specialized features of ANSYS CFX. Files required to complete each tutorial is listed in the introduction to the tutorial, and located in /examples , where is the installation directory.

Setting the Working Directory

One of the first things you must do when using ANSYS CFX is to set a working directory. The working directory is the default location for loading and saving files for a particular session or project. The working directory is set according to how you run ANSYS CFX:

• Workbench Set the working directory by saving a project file.
• Standalone Set the working directory by entering it in CFX Launcher.

Introduction to the ANSYS CFX Tutorials: Changing the Display Colors

Page 2 ANSYS CFX Tutorials. ANSYS CFX Release 11.0. © 1996-2006 ANSYS Europe, Ltd. All rights reserved. Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

Changing the Display Colors

If viewing objects in ANSYS CFX becomes difficult due to contrast with the background, the colors can be altered for improved viewing. The color options are set in different places, depending on how you run ANSYS CFX, as follows:

• In standalone mode (i.e., after using CFX Launcher to launch ANSYS CFX-Pre or ANSYS CFX-Post): a. Select Edit > Options. The Options dialog box appears. b. Adjust the color settings under CFX-Pre > Viewer (for ANSYS CFX-Pre) or CFX-Post > Viewer (for ANSYS CFX-Post). c. Click OK.
• In ANSYS Workbench: a. Select Tools > Options from the Project page. b. Adjust the color settings under Common Settings > Graphics Style. c. Click OK.

Tutorial 1: Simulating Flow in a Static Mixer Using CFX in Standalone Mode: Before You Begin

Page 4 ANSYS CFX Tutorials. ANSYS CFX Release 11.0. © 1996-2006 ANSYS Europe, Ltd. All rights reserved. Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

Before You Begin

Create a working directory for your files. Once this is done, copy the sample files used in this tutorial to your working directory from the installation folder for your software ( /examples/ (for example, C:\Program Files\ANSYS Inc\v110\CFX\examples )) to avoid overwriting source files provided with your installation. If you plan to use a session file, please refer to Playing a Session File (p. 7). Sample files used by this tutorial are:

• StaticMixerMesh.gtm
• StaticMixer.pre

Tutorial 1 Features

This tutorial addresses the following features of ANSYS CFX.

In this tutorial you will learn about:

• Using Quick Setup mode in ANSYS CFX-Pre to set up a problem.
• Modifying the outline plot in ANSYS CFX-Post.
• Using streamlines in ANSYS CFX-Post to trace the flow field from a point.
• Viewing temperature using colored planes and contours in ANSYS CFX-Post.
• Creating an animation and saving it to an MPEG file.

Component Feature Details ANSYS CFX-Pre User Mode Quick Setup Wizard Simulation Type Steady State Fluid Type General Fluid Domain Type Single Domain Turbulence Model k-Epsilon Heat Transfer Thermal Energy Boundary Conditions Inlet (Subsonic) Outlet (Subsonic) Wall: No-Slip Wall: Adiabatic Timestep Physical Time Scale ANSYS CFX-Post Plots Animation Contour Outline Plot (Wireframe) Point Slice Plane Streamline

Tutorial 1: Simulating Flow in a Static Mixer Using CFX in Standalone Mode: Overview of the Problem to Solve

ANSYS CFX Tutorials. ANSYS CFX Release 11.0. © 1996-2006 ANSYS Europe, Ltd. All rights reserved. Page 5 Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

Overview of the Problem to Solve

This tutorial simulates a static mixer consisting of two inlet pipes delivering water into a mixing vessel; the water exits through an outlet pipe. A general workflow is established for analyzing the flow of fluid into and out of a mixer. Water enters through both pipes at the same rate but at different temperatures. The first entry is at a rate of 2 m/s and a temperature of 315 K and the second entry is at a rate of 2 m/s at a temperature of 285 K. The radius of the mixer is 2 m. Your goal in this tutorial is to understand how to use ANSYS CFX to determine the speed and temperature of the water when it exits the static mixer. Figure 1 Static Mixer with 2 Inlet Pipes and 1 Outlet Pipe 2 m/s 285 K

2 m/s 315 K

r=2m

Tutorial 1: Simulating Flow in a Static Mixer Using CFX in Standalone Mode: Defining a Simulation in ANSYS CFX-Pre

ANSYS CFX Tutorials. ANSYS CFX Release 11.0. © 1996-2006 ANSYS Europe, Ltd. All rights reserved. Page 7 Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

6. Setting Boundary Data (p. 9)
7. Setting Flow Specification (p. 9)
8. Setting Temperature Specification (p. 10)
9. Reviewing the Boundary Condition Definitions (p. 10)
10. Creating the Second Inlet Boundary Definition (p. 10)
11. Creating the Outlet Boundary Definition (p. 10)
12. Moving to General Mode (p. 11)
13. Writing the Solver (.def) File (p. 11)

Playing a Session File

If you want to skip past these instructions and have ANSYS CFX-Pre set up the simulation automatically, you can select Session > Play Tutorial from the menu in ANSYS CFX-Pre, then run the appropriate session file. For details, see Playing the Session File and Starting ANSYS CFX-Solver Manager (p. 12). After you have played the session file, proceed to Obtaining a Solution Using ANSYS CFX-Solver Manager (p. 12).

Creating a New Simulation

Before importing and working with a mesh, a simulation needs to be started using Quick Setup mode.

Procedure 1. If required, launch ANSYS CFX-Pre.

2. Select File > New Simulation. The New Simulation File dialog box is displayed.
3. Select Quick Setup and click OK. Note: If this is the first time you are running this software, a message box will appear notifying you that automatic generation of the default domain is active. To avoid seeing this message again uncheck Show This Message Again.
4. Select File > Save Simulation As.
5. Under File name , type: StaticMixer
6. Click Save.

Setting the Physics Definition

You need to specify the fluids used in a simulation. A variety of fluids are already defined as library materials. For this tutorial you will use a prepared fluid, Water, which is defined to be water at 25°C.

Procedure 1. Ensure that Simulation Definition is displayed at the top of the details view.

2. Under Fluid select Water.

Importing a Mesh

At least one mesh must be imported before physics are applied.

Procedure 1. In Simulation Definition , under Mesh File , click Browse. The Import Mesh dialog box appears.

Tutorial 1: Simulating Flow in a Static Mixer Using CFX in Standalone Mode: Defining a Simulation in ANSYS CFX-Pre

Page 8 ANSYS CFX Tutorials. ANSYS CFX Release 11.0. © 1996-2006 ANSYS Europe, Ltd. All rights reserved. Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

2. Under File type , select CFX Mesh (*gtm *cfx).
3. From your working directory, select StaticMixerMesh.gtm.
4. Click Open. The mesh loads.
5. Click Next.

Using the Viewer

Now that the mesh is loaded, take a moment to explore how you can use the viewer toolbar to zoom in or out and to rotate the object in the viewer.

Using the Zoom Tools

There are several icons available for controlling the level of zoom in the viewer.

1. Click Zoom Box
2. Click and drag a rectangular box over the geometry.
3. Release the mouse button to zoom in on the selection. The geometry zoom changes to display the selection at a greater resolution.
4. Click Fit View to re-center and re-scale the geometry.

Rotating the geometry

If you need to rotate an object or to view it from a new angle, you can use the viewer toolbar.

1. Click Rotate on the viewer toolbar.
2. Click and drag within the geometry repeatedly to test the rotation of the geometry. The geometry rotates based on the direction of movement. Notice how the mouse cursor changes depending on where you are in the viewer:
3. Right-click a blank area in the viewer and select Predefined Camera > View Towards-X).
4. Right-click a blank area in the viewer and select Predefined Camera > Isometric View (Z Up). A clearer view of the mesh is displayed.