# PDE for Scientists and Engineers Farlow

• Applied
• DrPapper
In summary, the conversation discusses the use and effectiveness of the book "Partial Differential Equations for Scientists and Engineers" by Stanley J. Farlow. The person is unsure about the book's usefulness for self-study and struggles with solving problems from the book. However, they appreciate the book's approach and recommend it as a supplement to other texts. The conversation also includes a helpful tip for solving a specific problem in the book.

#### DrPapper

Hello Fellow Physics People,

I am just now taking a math methods course for Physicists and we're using Mary Boas book. I wanted to supplement it for better understanding as saw Partial Differential Equations for Scientists and Engineers by Stanley J. Farlow.

Reading reviews for this book on Amazon made me think, perfect for me. I've done well in Calculus and ODEs. So I pick it up and get to the problems at the end of lesson 1 and lesson 2 and think to myself "How the l;kj would I do these?" I look at the solutions and have no idea how they got to them for some of these.

So is this book really that good? Am I missing something? Should it be able to be used for self-study alone or in conjunction with another text?

In isolation of the info an average student would recall from calculus and ODEs and info in this book prior to other lessons how for example would you solve problem 2 in lesson 2:

Suppose the rod has a constant internal heat source, so the basic equation describing the heat flow within the rod is: Ut=a2Uxx+1

o<x<1

Suppose we fix the boundaries' temperatures by u(0,t)=0 and u(1,t)=0. What is the steady-state temperature of the rod? In other words, does the temperature u(x,t) converge to a constant temperature U(x) independent of time?

Hint: Set ut=0. It would be useful to graph this temperature. Also start with an initial temperature of zero and draw some temperature profiles.
<-----How do I even draw this?Let me note that Farlow uses Uxx to mean ∇2u and Ut to be the differential of U with respect to time. At least as far as I can see...

I read Farlow's book a lot of years ago and I sort of liked it (to the extent I bought it when I saw it on Amazon). It's not a monumental masterwork, nor a revered reference book on PDE: it's just a quick hands-on collection of (almost unabridged) essays on the most common methods of solutions for PDEs. I would not use this book as the only book on PDEs, but I would use it to get my feet wet before starting my journey into the PDE Realm.
The best feature of Farlow's book is that most of the chapters (or strings of two-three chapters) can be read in whichever order you like. It gives you an idea of what are and how to solve the most common PDEs without requiring higher level math. In that, it is exceptionally good.

You will have to fill in the gaps, though.

Steady state means u does not change with temperature - hence the hint to set Ut=0. So, what happens to the PDE when you set Ut=0?
It becomes an Ordinary Differential Equation in x. Solve that and you will find the shape of your solution (might have to guess a couple of constants...)
Can you plot these solutions?

P.S.
Sorry for being nit-picking but Uxx is not Farlow's convention for nabla square of U. It's just that the problem is one-dimensional in space and the Laplacian (in rectangular coordinates) reduces to Uxx

Last edited:
DrPapper
SredniVashtar said:
I read Farlow's book a lot of years ago and I sort of liked it (to the extent I bought it when I saw it on Amazon). It's not a monumental masterwork, nor a revered reference book on PDE: it's just a quick hands-on collection of (almost unabridged) essays on the most common methods of solutions for PDEs. I would not use this book as the only book on PDEs, but I would use it to get my feet wet before starting my journey into the PDE Realm.
The best feature of Farlow's book is that most of the chapters (or strings of two-three chapters) can be read in whichever order you like. It gives you an idea of what are and how to solve the most common PDEs without requiring higher level math. In that, it is exceptionally good.

You will have to fill in the gaps, though.

Steady state means u does not change with temperature - hence the hint to set Ut=0. So, what happens to the PDE when you set Ut=0?
It becomes an Ordinary Differential Equation in x. Solve that and you will find the shape of your solution (might have to guess a couple of constants...)
Can you plot these solutions?

P.S.
Sorry for being nit-picking but Uxx is not Farlow's convention for nabla square of U. It's just that the problem is one-dimensional in space and the Laplacian (in rectangular coordinates) reduces to Uxx
Thank you so much for your help. The last bit wasn't nit picky at all, it's good to know. :D

I guess I need to take a breather, I'm stressing on an upcoming test. Ha ha, that ODE conversion should have been appearant to me. LOL

THANKS AGAIN!

## What is the purpose of studying PDE for Scientists and Engineers Farlow?

The purpose of studying PDE (Partial Differential Equations) for Scientists and Engineers Farlow is to gain a deeper understanding of how to mathematically model and solve problems in the fields of science and engineering. PDEs are widely used to describe physical phenomena such as heat transfer, fluid dynamics, and quantum mechanics, making them essential tools for scientists and engineers.

## What are some common applications of PDE in science and engineering?

PDEs have a wide range of applications in various fields of science and engineering. Some common examples include modeling the spread of diseases, predicting weather patterns, designing aircraft wings, and simulating chemical reactions. PDEs are also used in the development of computer algorithms and image processing techniques.

## How does PDE differ from other types of differential equations?

PDEs are differential equations that involve multiple independent variables, such as time and space. This makes them more complex than ordinary differential equations, which only involve one independent variable. PDEs also have a wide variety of boundary conditions, making them more challenging to solve and requiring different techniques and methods.

## What skills are required to understand and solve PDEs?

To understand and solve PDEs, one needs a strong foundation in mathematics, particularly in calculus, linear algebra, and differential equations. It is also essential to have a good understanding of physical principles and their applications in science and engineering. Additionally, knowledge of computer programming and numerical methods is beneficial in solving PDEs numerically.

## What are some recommended resources for learning PDE for Scientists and Engineers Farlow?

Some recommended resources for learning PDE include textbooks such as "Partial Differential Equations for Scientists and Engineers" by Stanley J. Farlow, online courses and tutorials, and practice problems and exercises. It is also helpful to consult with professors or peers who have expertise in the field and can provide guidance and support in understanding and solving PDEs.