# Is Dynamics important for Fluid Mechanics?

1. Apr 30, 2013

### hitman_47

Hey Guys,

I am supposed to take Fluid Mechanics in Fall 2013. The course has lots of prerequisites and I have taken them all.

One of the prerequisites is Dynamics. In Dynamics I was taught how to analyze objects in motion using Newton's Second Law of motion, Work and Energy method and Impulse and Momentum. The course first started with Particle Dynamics then it moved onto Rigid Body Dynamics. The only difference is Rigid Body dynamics was we could no longer ignore the geometry of the object and thus had to extend the concepts in particle dynamics.

I am very good with Particle Dynamics but I have some weaknesses with Rigid Body Dynamics. In Rigid body dynamics, I was making conceptual mistakes and taking way too long to solve problems.

Now my questions are

1. Will my weakness in Rigid Body Dynamics prevent from mastering Fluid Mechanics?
2. What course (or topics) is crucial to understand before taking Fluid Mechanics?

2. May 1, 2013

### Autosug

If you can squeeze a thermodynamics course in it probably would be good. I had thermodynamics and Fluid mechanics at the same time and i wish Id had thermo prior to fluid. It made things harder.
Had dynamics prior to these courses.
:)

3. May 1, 2013

### Staff: Mentor

Fluid dynamics applies Newton's second law to differential elements of fluid, rather than to entire bodies. Each an every parcel of fluid is subjected to Newton's second law. So the dynamics part of your background should help. But, in fluid mechanics, you are also going to be dealing with materials that are deforming, and you are going to make the acquaintance of the stress tensor. Although not imperative, it might be useful to take a course in strength of materials (solid mechanics) which might help introduce you to the stress tensor.

4. May 1, 2013

Rule #1: F = ma

That's all dynamics really is, including fluid dynamics. The difference is that there is just a different constitutive equation for a fluid than for a rigid body, so the solutions are different.

5. Jun 19, 2013

### caldweab

I highly recommend taking thermodynamics and heat transfer first. Heat transfer gradually moves into fluid dynamics when you get to convection and the boundary layers. On topic though, you'll be fine with your dynamics background.

6. Jun 25, 2013

### justin22

Whenever your dealing with fluid mechanics you will be dealing with energy balance equations, bernoilli's principle and equation, static analysis, and some simple fluid dynamic analysis. Introduction to Thermodynamics courses usually cover some fluid mechanics principles. Heat transfer courses would only be beneficial if you are taking a fluid dynamics course. I do not believe you are at a disadvantage with your weakness. Keep an open mind when learning a new topic. Fluid mechanics is an interesting field of study and can be implemented to a significant amount of real world engineering situations. Best of luck.

7. Jun 26, 2013

### Ritz_physics

The mechanics of fluids is different from that of rigid bodies, even though both are governed by Newton's laws. The approach to analyzing "flow" is different as well. So your weakness in rigid body dynamics will not affect this course at all.
However take this tip: Fluid Dynamics involves study of continuum, ie. simply speaking "continuous force fields". I guess this phrase might be a little intimidating at first, but this can be one the easiest subjects you ever learnt if you are good with calculus. So it is of utmost importance that you are atleast well-acquainted with multi-variable calculus. You will be using it quite often.