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Transcript of ANSYS FLUENT 12 - FLUENT 12.0 Magnetohydrodynamics ... any form without express written permission...

  • ANSYS FLUENT 12.0

    Magnetohydrodynamics (MHD)

    Module Manual

    January 2009

  • Copyright c 2009 by ANSYS, Inc.All Rights Reserved. No part of this document may be reproduced or otherwise used in

    any form without express written permission from ANSYS, Inc.

    Airpak, Mechanical APDL, Workbench, AUTODYN, CFX, FIDAP, FloWizard, FLUENT,GAMBIT, Iceboard, Icechip, Icemax, Icepak, Icepro, Icewave, MixSim, POLYFLOW, TGrid,

    and any and all ANSYS, Inc. brand, product, service and feature names, logos andslogans are registered trademarks or trademarks of ANSYS, Inc. or its subsidiaries

    located in the United States or other countries. All other brand, product, service andfeature names or trademarks are the property of their respective owners.

    CATIA V5 is a registered trademark of Dassault Systemes. CHEMKIN is a registeredtrademark of Reaction Design Inc.

    Portions of this program include material copyrighted by PathScale Corporation2003-2004.

    ANSYS, Inc.Centerra Resource Park

    10 Cavendish CourtLebanon, NH 03766

  • Contents

    Preface UTM-1

    1 Introduction 1-1

    2 Magnetohydrodynamic Model Theory 2-1

    2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

    2.2 Magnetic Induction Method . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

    2.2.1 Case 1: ~B0 Generated in Non-conducting Media . . . . . . . . . 2-3

    2.2.2 Case 2: ~B0 Generated in Conducting Media . . . . . . . . . . . . 2-4

    2.3 Electric Potential Method . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

    3 Implementation 3-1

    3.1 Solving Magnetic Induction and Electric Potential Equations . . . . . . . 3-1

    3.2 Calculation of MHD Variables . . . . . . . . . . . . . . . . . . . . . . . . 3-2

    3.3 MHD Interaction with Fluid Flows . . . . . . . . . . . . . . . . . . . . . 3-2

    3.4 MHD Interaction with Discrete Phase Model . . . . . . . . . . . . . . . 3-3

    3.5 General User-Defined Functions . . . . . . . . . . . . . . . . . . . . . . . 3-3

    4 Using the ANSYS FLUENT MHD Module 4-1

    4.1 MHD Module Installation . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

    4.2 Loading the MHD Module . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

    4.3 MHD Model Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

    4.3.1 Enabling the MHD Model . . . . . . . . . . . . . . . . . . . . . . 4-3

    4.3.2 Selecting an MHD Method . . . . . . . . . . . . . . . . . . . . . 4-5

    4.3.3 Applying an External Magnetic Field . . . . . . . . . . . . . . . 4-5

    4.3.4 Setting Up Boundary Conditions . . . . . . . . . . . . . . . . . . 4-9

    Release 12.0 c ANSYS, Inc. January 5, 2009 i

  • CONTENTS

    4.3.5 Solution Controls . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13

    4.4 MHD Solution and Postprocessing . . . . . . . . . . . . . . . . . . . . . 4-14

    4.4.1 MHD Model Initialization . . . . . . . . . . . . . . . . . . . . . . 4-14

    4.4.2 Iteration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14

    4.4.3 Postprocessing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15

    4.5 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16

    A Guidelines For Using the ANSYS FLUENT MHD Model A-1

    A.1 Installing the MHD Module . . . . . . . . . . . . . . . . . . . . . . . . . A-1

    A.2 An Overview of Using the MHD Module . . . . . . . . . . . . . . . . . . A-2

    B Definitions of the Magnetic Field B-1

    B.1 Magnetic Field Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

    C External Magnetic Field Data Format C-1

    C.1 Magnetic Field Data Format . . . . . . . . . . . . . . . . . . . . . . . . C-1

    D MHD Module Text Commands D-1

    ii Release 12.0 c ANSYS, Inc. January 5, 2009

  • Using This Manual

    The Contents of This Manual

    The ANSYS FLUENT Magnetohydrodynamics (MHD) Module Manual tells you what youneed to know to model magnetohydrodynamics with ANSYS FLUENT. In this manual,you will find background information pertaining to the model, a theoretical discussion ofthe model used in ANSYS FLUENT, and a description of using the model for your CFDsimulations.

    Typographical Conventions

    Several typographical conventions are used in this manuals text to facilitate your learningprocess.

    An informational icon ( i ) marks an important note.

    A warning icon ( ! ) marks a warning.

    Different type styles are used to indicate graphical user interface menu items andtext interface menu items (e.g., Iso-Surface dialog box, surface/iso-surface com-mand).

    The text interface type style is also used when illustrating exactly what appearson the screen or exactly what you need to type into a field in a dialog box. Theinformation displayed on the screen is enclosed in a large box to distinguish it fromthe narrative text, and user inputs are often enclosed in smaller boxes.

    A mini flow chart is used to guide you through the navigation pane, which leadsyou to a specific task page or dialog box. For example,

    Models Multiphase Edit...indicates that Models is selected in the navigation pane, which then opens thecorresponding task page. In the Models task page, Multiphase is selected from thelist. Clicking the Edit... button opens the Multiphase dialog box.

    Release 12.0 c ANSYS, Inc. January 5, 2009 UTM-1

  • Using This Manual

    Also, a mini flow chart is used to indicate the menu selections that lead you to aspecific command or dialog box. For example,

    Define Injections...indicates that the Injections... menu item can be selected from the Define pull-downmenu, and

    display meshindicates that the mesh command is available in the display text menu.

    In this manual, mini flow charts usually precede a description of a dialog box orcommand, or a screen illustration showing how to use the dialog box or command.They allow you to look up information about a command or dialog box and quicklydetermine how to access it without having to search the preceding material.

    The menu selections that will lead you to a particular dialog box or task pageare also indicated (usually within a paragraph) using a /. For example, De-fine/Materials... tells you to choose the Materials... menu item from the Definepull-down menu.

    Mathematical Conventions Where possible, vector quantities are displayed with a raised arrow (e.g., ~a, ~A).

    Boldfaced characters are reserved for vectors and matrices as they apply to linearalgebra (e.g., the identity matrix, I).

    The operator , referred to as grad, nabla, or del, represents the partial derivativeof a quantity with respect to all directions in the chosen coordinate system. InCartesian coordinates, is defined to be

    x~ +

    y~ +

    z~k

    appears in several ways:

    The gradient of a scalar quantity is the vector whose components are thepartial derivatives; for example,

    p = px

    ~ +p

    y~ +

    p

    z~k

    UTM-2 Release 12.0 c ANSYS, Inc. January 5, 2009

  • Using This Manual

    The gradient of a vector quantity is a second-order tensor; for example, inCartesian coordinates,

    (~v) =(

    x~ +

    y~ +

    z~k

    )(vx~ + vy~ + vz~k

    )This tensor is usually written as

    vxx

    vxy

    vxz

    vyx

    vyy

    vyz

    vzx

    vzy

    vzz

    The divergence of a vector quantity, which is the inner product between

    and a vector; for example,

    ~v = vxx

    +vyy

    +vzz

    The operator , which is usually written as 2 and is known as theLaplacian; for example,

    2T = 2T

    x2+

    2T

    y2+

    2T

    z2

    2T is different from the expression (T )2, which is defined as

    (T )2 =(

    T

    x

    )2+

    (T

    y

    )2+

    (T

    z

    )2

    Release 12.0 c ANSYS, Inc. January 5, 2009 UTM-3

  • Using This Manual

    Technical Support

    If you encounter difficulties while using ANSYS FLUENT, please first refer to the section(s)of the manual containing information on the commands you are trying to use or the typeof problem you are trying to solve. The product documentation is available from theonline help, or from the User Services Center (www.fluentusers.com).

    If you encounter an error, please write down the exact error message that appeared andnote as much information as you can about what you were doing in ANSYS FLUENT. Thenrefer to the following resources available on the User Services Center (www.fluentusers.com):

    Installation and System FAQs - link available from the main page on the UserServices Center. The FAQs can be searched by word or phrase, and are availablefor general installation questions as well as for products.

    Known defects for ANSYS FLUENT - link available from the product page. Thedefects can be searched by word or phrase, and are listed by categories.

    Online Technical Support - link available from the main page on the User ServicesCenter. From the Online Technical Support Portal page, there is a link to theSearch Solutions & Request Support page, where the solutions can be searched byword or phrase.

    Contacting Technical Support

    If none of the resources available on the User Services Center help in resolving the prob-lem, or you have complex modeling projects, we invite you to log a technical supportrequest (www.fluentusers.com) to obtain further assistance. However, there are a fewthings that we encourage you to do before logging a request:

    Note what you are trying to accomplish with ANSYS FLUENT.

    Note what you were doing when the problem or error occurred.

    Save a journal or transcript file of the ANSYS FLUENT