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COMSOL®
FOR Engineers
Mehrzad Tabatabaian
MERCURY LEARNING AND INFORMATION
Dulles, Virginia
Boston, Massachusetts
New Delhi
Copyright ©2014 by Mercury Learning and Information. All rights reserved.
This publication, portions of it, or any accompanying software may not be reproduced in any
way, stored in a retrieval system of any type, or transmitted by any means, media, electronic
display or mechanical display, including, but not limited to, photocopy, recording, Internet
postings, or scanning, without prior permission in writing from the publisher.
Publisher: David Pallai
Mercury Learning and Information
22841 Quicksilver Drive
Dulles, VA 20166
info@merclearning.com
www.merclearning.com
1-800-758-3756
This book is printed on acid-free paper.
M. Tabatabaian. COMSOL® for Engineers.
ISBN: 978-1-938549-53-3
The publisher recognizes and respects all marks used by companies, manufacturers, and
developers as a means to distinguish their products. All brand names and product names
mentioned in this book are trademarks or service marks of their respective companies.
Any omission or misuse (of any kind) of service marks or trademarks, etc. is not an attempt
to infringe on the property of others.
Library of Congress Control Number: 2013958000
141516321
Our titles are available for adoption, license, or bulk purchase by institutions, corporations, etc.
For additional information, please contact the Customer Service Dept. at 1-800-758-3756
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The sole obligation of Mercury Learning and information to the purchaser is to
replace the disc, based on defective materials or faulty workmanship, but not based on
the operation or functionality of the product.
To the memories of my father,
whose support and guidance are still felt to this day.
To my family, for their support and encouragement.
CONTENTS
Preface
Chapter 1: Introduction
Chapter 2: Finite Element Method—A Summary
Overview
FEM Formulation
Matrix Approach
Example 2.1: Analysis of a 2D Truss
General Procedure for Global Matrix Assembly
Example 2.2: Global Matrix for Triangular Elements
Weighted Residual Approach
Galerkin Method
Shape Functions
Convergence and Stability
Example 2.3: Heat Transfer in a Slender Steel Bar
Exercise Problems
References
xi
1
5
5
8
9
9
13
14
15
15
16
17
18
21
21
viii • Contents
Chapter 3: COMSOL—A Modeling Tool for Engineers
Overview
COMSOL Interface
COMSOL Modules
COMSOL Model Library and Tutorials
General Guidelines for Building a Model
Chapter 4: COMSOL Models for Physical Systems
Overview
Section 4.1: Static and Dynamic Analysis of Structures
Example 4.1: Stress Analysis for a Thin Plate Under
Stationary Loads
Example 4.2: Dynamic Analysis for a Thin Plate: Eigenvalues
and Modal Shapes
Example 4.3: Parametric Study for a Bracket Assembly:
3D Stress Analysis
Example 4.4: Buckling of a Column with Triangular
Cross-section: Linearized Buckling Analysis
Example 4.5: Static and Dynamic Analysis for a 2D
Bridge-support Truss
Example 4.6: Static and Dynamic Analysis for a 3D Truss Tower
Section 4.2: Dynamic Analysis and Models of
Internal Flows: Laminar and Turbulent
23
23
24
32
33
34
37
37
38
38
49
53
67
76
88
95
Example 4.7: Axisymmetric Flow in a Nozzle:
96
Simplified Water-jet
Example 4.8: Swirl Flow Around a Rotating Disk: Laminar Flow
105
Example 4.9: Swirl Flow Around a Rotating Disk: Turbulent Flow 114
Example 4.10: Flow in a U-shape Pipe with Square
Cross-sectional Area: Laminar Flow
Example 4.11: Double-driven Cavity Flow:
Moving Boundary Conditions
118
129
Contents • ix
Example 4.12: Water Hammer Model: Transient Flow Analysis
Example 4.13: Static Fluid Mixer Model
Section 4.3: Modeling of Steady and Unsteady Heat
Transfer in Media
Example 4.14: Heat Transfer in a Multilayer Sphere
Example 4.15: Heat Transfer in a Hexagonal Fin
Example 4.16: Transient Heat Transfer Through a
Nonprismatic Fin with Convective Cooling
Example 4.17: Heat Conduction Through a Multilayer
Wall with Contact Resistance
Section 4.4: Modeling of Electrical Circuits
Example 4.18: Modeling an RC Electrical Circuit
Example 4.19: Modeling an RLC Electrical Circuit
Section 4.5: Modeling Complex and
Multiphysics Problems
Example 4.20: Stress Analysis for an Orthotropic Thin Plate
Example 4.21: Thermal Stress Analysis and Transient
Response of a Bracket
Example 4.22: Static Fluid Mixer with Flexible Baffles
Example 4.23: Double Pendulum: Multibody Dynamics
Example 4.24: Multiphysics Model for
Thermoelectric Modules
Example 4.25: Acoustic Pressure Wave Propagation
in an Automotive Muffler
Exercise Problems
References
Suggested Further Readings
Trademark References
Index
142
150
159
159
165
173
180
185
185
188
193
194
197
205
214
219
228
238
243
244
244
245
PREFACE
This book is written for engineers, engineering students, and other
practitioners in engineering fields. The main objective of the material
is to introduce and help readers to use COMSOL as an engineering
tool for modeling by solving examples that either directly could be used or
could become a guide for modeling similar or more complicated problems.
It would be exhaustive to include all features available in COMSOL in a
single book; our objective is to provide a collection of examples and model-
ing guidelines through which readers could build their own models.
Readers are assumed to know or at least be familiar with the princi-
ples of numerical modeling and finite element method (FEM). We took a
flexible-level approach for presenting the materials along with using practi-
cal examples. The mathematical fundamentals, engineering principles, and
design criteria are presented as integral parts of examples. At the end of
each chapter we have added references that contain more in-depth physics,
technical information, and data; these are referred to throughout the book
and used in the examples. This approach allows readers to learn the materi-
als at their desired level of complexity.
COMSOL for Engineers could be used as a textbook complementing
another text that provides background training in engineering computa-
tions and methods, such as FEM. Examples provided in this book should be
considered as “lessons” for which background physics could be explained
in more detail. Exercise problems, or their variations, could be used for
homework assignments.
We start each chapter with an overview, background physics, and
mathematical models to set the foundation. We then present the relevant
modeling techniques and materials through several examples. The examples