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July 13, 2006, 09:03 
BATCH PROCCESSING

#1 
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I have made pressure loss calculations with ansys cfx. I have programmed the basic darcy weisbach equation in order to get such losses. I have validated it comparing the results of the simulation with calculations by hand using the same model. The proccess is as follows:
1. I have done a model of a straight tube. 2. I have given as constant value for the problem the friction factor in darcyweisbach equation. This factor can be obtained by use of Moody's chart, but I want to use the cfx capabilities in order it can calculate it directly. so I have an equation that gives the same result than Moody's chart. This is the colebrookwhite equation. This equation solves the friction factor as a funtion of itself, so if you want to solve it you must solve it by iteration. This is the first question: Is there anybody who knows how can i program an iteration in ansys cfx? colebrookwhite equation is as follows: 1/sqrt(lambda)=2*log(k/(3.7*D)+2.51/(Re*sqrt(lambda))) The second problem is the following: I have given initial conditions to the model. I have specified a determined flow rate, but it's constant. So if i want to obtain pressure losses for several flow rates I should run the same simulation several times varying the flow rates in ordel to get such losses. The question is: Is there any way to do this in such a way that I can specifiy a flow rate range and ansys can execute the simulation in the flow range specified? How could I program a bath proccess in ansys cfx? Thanks in advance 

July 14, 2006, 01:19 
Re: BATCH PROCCESSING

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Batch mode: CFX Community, Technical Tips: Running solver jobs in batch and job scheduling 27 October 2005


July 14, 2006, 10:04 
Re: BATCH PROCCESSING

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More commands can be viewed from the command line (DOS window) started through CFX launcher by running:
cfx5solve help 

July 14, 2006, 12:23 
Re: BATCH PROCCESSING

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Hi Roberto,
I'm not sure I understand what you are trying to do. Are you calculating the friction factor to apply at a boundary condition? To calculate the friction factor directly, use the SwameeJain equation instead http://en.wikipedia.org/wiki/SwameeJain_equation. Regards, Robin 

July 15, 2006, 12:22 
Re: BATCH PROCCESSING

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Hi, Robin. I have seen the SwameeJain ecuation, and I have validated it by comparing it with the colebrook white ecuation. I have found that it gives results within 0.0001 accuracy so this time you have helped me to solve the friction factor without the use of iterative proccesses.
So now I need to investigate the advice given to me respect to batch proccessing. 

July 15, 2006, 12:30 
Re: BATCH PROCCESSING

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Hi Patrick, where should I find the document that you are refering to?


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