large eddy simulation(LES) for turbomachinary
 

Hi all
I have a question for using LES in a turbomachinary. Normally, we impose "Total Pressure","Total Temprature" and "Flow Angle" as inlet boundary conditions (subsonic). So , if I impose these as inlet boundary conditions, how could I impose velocity fluctuations at inlet ?
May I give some fluctuations on Total Pressure or Total Temprature ?? Can anyone gime me the answer or some recommendation?

An easy to implement an obvious way ist to calculate small timesteps and modify the U file in the latestTime dir. Your controldict.startFrom should contain "latestTime".

Thank you for your answers ! But sorry, I don't quite understand. Could you please make it clear?

If you start the simulation you have to give initial values for U and p in the 0 directory. After running the simulation for a simulated time you get results in a directory which is named by the simulated time. This contains p and U.
If you change the values to the ones you want to haveand restart the simulation, these values will be used from this simulated time on.

I agree with PIU58 the problem with LES are the boundary and initial conditions. For subsonic flows you can specify velocities at the inlet, why don't tu work with velocities instead ? Nonetheless, you can follow PIU58 recommendations.

Thank you ! I will try it.

Sorry for late reply. In my simulation, the flow is transonic. I want to use LES method, and compare the result with the experimental data. But in the experiment, the total pressure,total temprature,and flow angle are specified at the inlet. How should I specify the inlet velocities instead ?
I can find the Mach Number distribution at the inlet from the experimental data. Can I get the velocity and static pressure distributions by using isentropic relations ?

> in the experiment, the total pressure,total temprature,and flow angle are specified at the inlet.

In this case you define the pressure at the inlet and the outlet (probably 0 there). For the velocity you give the gradient: zero gradient at the outlet and the gradient according to your inflow angle for the inlet.