[rkadlof]

Hello,

I learn Ansys Fluent on my own. Read PDF's book etc. However I cannot find the simple answer for few questions.
I understand the ideas of RANS, DNS, LES methods, but (maybe it is a stupid question)

1. How do I know which one method is running during computation? Does it depend on eq. turbulence model? mesh size? There is somewhere kinda option to switch on eg. LES instead of RANS?

2. Second question, I am going to do simulation of PDE, RDE, or pulsejet in fluent. How to represent the valves (open-close), do i need to make the UDF with eq. function "if pressure <1atm blabla" or is that possible to achieve by creating dynamic mesh?

I hope it is clear enough to understand.
Thank you for attention ;-)
R.

[ghost82]

Originally Posted by rkadlof

Hello,

I learn Ansys Fluent on my own. Read PDF's book etc. However I cannot find the simple answer for few questions.
I understand the ideas of RANS, DNS, LES methods, but (maybe it is a stupid question)

1. How do I know which one method is running during computation? Does it depend on eq. turbulence model? mesh size? There is somewhere kinda option to switch on eg. LES instead of RANS?

R.

Hi,
when you choose the viscous model (turbulence/laminar models) in the viscous model tab, if you go for turbulence model, you choose between RANS and LES (large eddy simulation).
k-epsilon, k-omega, etc. are all RANS simulations.
Obviously you need mesh size depending on the turbulence model (and wall treatment).

For DNS read here to have really basic concepts:
http://www.cfd-online.com/Forums/flu...nt-15-0-a.html

[rkadlof]

You're right. Thank you for answer ;-)