Computational Fluid Dynamics and COMSOL Multiphysics

A Step-by-Step Approach for Chemical Engineers

Ashish S. Chaurasia

• Publisher: Apple Academic Press
• Year: 2021
• Print ISBN: 9781774639320
• eBook ISBN: 9781000400922
• Edition: 1
• Topic: Computer Science
• Subtopic: Software Development
• Index: Computer Science

This textbook covers computational fluid dynamics simulation using COMSOL Multiphysics® Modeling Software in chemical engineering applications. In the volume, the COMSOL Multiphysics package is introduced and applied to solve typical problems in chemical reactors, transport processes, fluid flow, and heat and mass transfer.

Inspired by the difficulties of introducing the use of COMSOL Multiphysics software during classroom time, the book incorporates the author's experience of working with undergraduate, graduate, and postgraduate students to make the book user friendly and that, at the same time, addresses typical examples within the subjects covered in the chemical engineering curriculum. Real-world problems require the use of simulation and optimization tools, and this volume shows how COMSOL Multiphysics software can be used for that purpose.

Key features:
• Includes over 500 step-by-step screenshots
• Shows the graphical user interface of COMSOL, which does not require any programming effort
• Provides chapter-end problems for extensive practice along with solutions
• Includes actual examples of chemical reactors, transport processes, fluid flow, and heat and mass transfer

This book is intended for students who want or need more help to solve chemical engineering assignments using computer software. It can also be used for computational courses in chemical engineering. It will also be a valuable resource for professors, research scientists, and practicing engineers.

CHAPTER 1 Introduction

The past three decades have witnessed the phenomenal growth in the area of computational fluid dynamics (CFD) due to the developments in the field of computers. CFD has now become the integral part the way engineers design and analyze the processes. The engineers can make use of CFD tools to simulate the reaction kinetics, fluid flow, and heat transfer processes in the design and predict the process performance before production. The advantages of using CFD tools include very high speed of computing, much cheaper than setting up big experiments or building prototypes, allows numerical experimentation, and so on.

The aim of this book is to provide the use of COMSOL Multiphysics software in chemical engineering applications so that students become familiar with the capabilities. This book solves typical problems in chemical reactors, transport processes, fluid flow, and heat and mass transfer using most popular commercial COMSOL Multiphysics software. It also discusses the real-world problems that require the use of simulation and optimization tools. The book is organized into seven chapters.

Chapter 2 deals with methods to model chemical reactors using differential and algebraic equations:

$u\frac{d{C}_A}{dz}=-2k{C}_{A,s}^2,u\frac{d{C}_B}{dz}=+k{C}_{A,s}^2,u\frac{d{C}_C}{dz}=0$ (1.1)

$C_A\left(0\right)=2kmol/m^3,C_B\left(0\right)=0,C_C\left(0\right)=2kmol/m^3.$ (1.2)

In the differential equation (1.1), the dependent variables C_A, C_B and C_C are functions of independent variable z. The concentrations of different species in the reactor can be determined using initial conditions given in Equation (1.2)

$148,4=\frac{\left(x/2\right)\left(x/2\right)}{\left[\left(1-x\right)/2\right]\left[\left(1-x\right)/2\right]}.$ 1.3

Equation (1.3) is nonlinear and can be solved by taking an appropriate initial guess value of x

$120c1-20c2=400$ (1.4)

$c1-c2=0$ (1.5)

$40c1+60c2-120c2=-200.$ (1.6)

Equations (1.4)–(1.6) represent the linear algebraic equations for three reactors linked by the pipes and can be solved for concentrations c1, c2, and c3.

Chapter 3 deals with problems in transport processes in one dimension considering steady and transient state. Consider a hot infinite plate of finite thickness having insulation condition on the left boundary and dimensionless temperature θ = 0 at the other boundary with initial condition θ (X, 0) = 1. The governing differential equation is

$\begin{array}{l}\frac{\partial \theta }{\partial \tau }=\alpha \frac{{\partial }^2\theta }{\partial X^2}\\ where,a=2,\theta =\frac{T-T_{\infty }}{T_i-T_{\infty }},X=\frac{x}{L},\tau =\frac{\alpha t}{L^2}\end{array}$ (1.7)

Equation (1.7) is a partial differential equation with a dependent variable θ, which varie...

Table of contents

• Cover Page
• Half-Title Page
• Title Page
• Copyright Page
• About the Author
• Table of Contents
• Abbreviations
• Preface
• 1. Introduction
• 2. Chemical Reactors
• 3. Transport Processes
• 4. Fluid Flow
• 5. Heat and Mass Transfer Processes in 2D and 3D
• 6. Optimization
• 7. Case Studie
• References
• Index