Many of us have heard about CFD. You might have come across a fancy poster at a symposium or a cool looking video or an image on YouTube. The complex cool looking images can be the first thing that attracts you towards CFD. Once you find yourself attracted, what do you do next ? If you start reading about it in Wikipedia, you will find yourself following each and every link on the resulting page and at the end be reading an article that is so far off from the main topic. Sounds familiar?
This has happened to us as well. With the abundance of information online, it is very hard to get access to structured content that provides a satisfying reading experience for a broad range of audience. My aim here is to assemble a set of steps that a CFD enthusiast can read while having their cup of tea. I will try my best to make you feel comfortable with the topics that are discussed.
We will try to explain to you about how you can learn CFD. Yes, we will actually provide a work plan that you can follow. The end result that we hope you will obtain is a clear understanding of what CFD is and feel comfortable about reading some of the other advanced topics. Once you are there, we believe that you will have the confidence to navigate through advanced topics in this area without getting lost in the wealth of information, the internet provides, in this topic.
Just like muscle-building, learning a new skill starts with setting up a reasonable goal based on your current capabilities are. When it comes to CFD, you have to first know “what you already know” and “what you don’t know”
To make it easy for the reader, we have compiled a list of topics that a CFD enthusiast needs to know to get started with CFD. The list is categorized based on the core subject area.
- Understand concepts such as density, pressure, and viscosity
- Non-dimensional numbers (Reynolds number, Peclet number and so on…)
- Shear stress, strain
- Fundamental governing equations in fluid mechanics
- Ability to perform dimensional analysis with ease
- Understanding of a control volume
- Linear algebra – Gauss elimination, Rank of a matrix, Eigen Values, and Vectors
- Vector calculus – Understanding the importance of normals and the calculation to compute them. Gradient and Divergence operators.
- Ordinary Differential Equations (ODEs)
- Partial Differential Equations (PDEs)
- Having a general idea about the concept of discretization.
That is basically the list of topics that you need to be familiar with to embark on your journey to learn CFD
That doesn’t sound that bad right? Or at least, you thought that getting started on CFD was more complex that the process that we had just put together.
When you break down a subject that feels complex into simple steps, you will actually know why you had so much difficulty in processing this topic before. Often times the biggest hurdle in the learning process is just in your mind. You can cross it by just breaking the problem into bits and then working on the bits, one at a time.
If you have completed at least 4 semesters of undergraduate education and majored in Mechanical, Aerospace or Automobile Engineering, you would have studied the above topics. If you remember the topics and can answer the following questions quite easily then start reading “Computational Fluid Dynamics, The basics with Applications by John D Anderson”
Questions that you need to be able to answer
- What is the difference between divergence and gradient operator
- Assume that there is a triangle in 3D space. You know the coordinates of the 3 points that make up this triangle. Compute the normal of the triangle.
- Can you write down Gauss’s Divergence theorem?
- What does total derivative mean?
- How to determine if a PDE is Hyperbolic, Parabolic or Ellipitic ?
- What does inviscid flow mean?
- What is the relationship between flow separation and wake region?
- What is the difference between static and dynamic pressure?
- What are the Euler Equations?
If you are unable to answer any of the questions, then you need to work for a couple of weeks by working on Linear Algebra, Vector Calculus, and Fluid Mechanics.
If you are able to answer all Math questions, then you need work for 3-4 days familiarizing yourself with the concepts from a good Fluids book.
If you are good at fluids and bad at Math, you need to work on Linear Algebra and Vector Calculus for at least 10 days.
Your training needs to be rigorous and focused. You need to spend 3 to 4 hours per day.
Here is a list of good books that you can use to get started on this journey. I will see you guys in the next blog post.
- Engineering Mathematics by Kreyzig – Vector calculus & Linear Algebra
- Fluid Mechanics by Frank M White
- Computational Fluid Dynamics, The basics with Applications – John D Anderson