how extract pressure fluctuation in cfx?

hamidciv · February 12, 2015, 17:15

hi dear friends

i run model free surface shown in cfx, now i want obtain pressure fluctuation, i using of chart for this mean, but i want have in number form, please help me.
i have full coordintes of points for extract.
i read cfx tutorial , but unfortunately problem not solved.
i have one another question, for evaluation pressure fluctuation,What is the turbulence model is used?
thanks a lot

ghorrocks · February 13, 2015, 04:46

* Put a monitor point where you want it
* Define the monitor point to extract the pressure
* Run the simulation
* In Solver Manager make a new monitor with your monitor point.
* Right click on the monitor and choose export.

What pressure fluctuation do you mean? The pressure fluctuation as modelled (that is of the mean flow)? Or do you mean the pressure fluctuations which average to zero in the Reynolds Averaged Navier Stokes equations?

hamidciv · February 13, 2015, 07:42

dear ghorrocks
my mean of pressure flactuation is changes pressure flow in time and extract max & min value for compare to experimental value? I already analyze model with k-epsilon, now i want working on pressure flactuation in bucket spillway,
My question is, which model get more exact result???
already mentioned in a post According to your order, les is suitable for this mean, in cfx exist multiple les(les smagorinsky, les wale, les dynamic model) Which of these Your order has been?
thanks a lot for help me

ghorrocks · February 13, 2015, 18:28

My previous post showed how to extract the pressure history at a single point. From there you can extract max, min, RMS averages and anything else you wish to do.

You can do this for the entire flow domain using transient statistics. Have a look in the output tab of CFX-Pre for this.

Your other question: k-epsilon, LES and other models - there is no simple answer to that question which is why many models exist. They all have strengths and weaknesses. I strongly recommend you do some reading about these models so you understand them so you can make up your own mind. Choosing from a position of knowledge is far better than blindly choosing options you do not understand.

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February 13, 2015, 04:46		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,728 Rep Power: 143	* Put a monitor point where you want it * Define the monitor point to extract the pressure * Run the simulation * In Solver Manager make a new monitor with your monitor point. * Right click on the monitor and choose export. What pressure fluctuation do you mean? The pressure fluctuation as modelled (that is of the mean flow)? Or do you mean the pressure fluctuations which average to zero in the Reynolds Averaged Navier Stokes equations?

February 13, 2015, 07:42		#3
hamidciv Senior Member Hydreaulic structures Join Date: Sep 2012 Posts: 283 Rep Power: 14	dear ghorrocks my mean of pressure flactuation is changes pressure flow in time and extract max & min value for compare to experimental value? I already analyze model with k-epsilon, now i want working on pressure flactuation in bucket spillway, My question is, which model get more exact result??? already mentioned in a post According to your order, les is suitable for this mean, in cfx exist multiple les(les smagorinsky, les wale, les dynamic model) Which of these Your order has been? thanks a lot for help me

February 13, 2015, 18:28		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,728 Rep Power: 143	My previous post showed how to extract the pressure history at a single point. From there you can extract max, min, RMS averages and anything else you wish to do. You can do this for the entire flow domain using transient statistics. Have a look in the output tab of CFX-Pre for this. Your other question: k-epsilon, LES and other models - there is no simple answer to that question which is why many models exist. They all have strengths and weaknesses. I strongly recommend you do some reading about these models so you understand them so you can make up your own mind. Choosing from a position of knowledge is far better than blindly choosing options you do not understand.