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-   -   Calculating Pressure Drop (http://www.cfd-online.com/Forums/cd-adapco/56439-calculating-pressure-drop.html)

M January 30, 2008 13:34

Calculating Pressure Drop
 
Hello,

I've got a curved pipe section with cyclic boundaries set at either end. The boundaries have a prescribed massflow rate, and I would like to be able to output the average Pressure Drop across the pipe. I thought you could output the area averaged Pressure across the inlet and outlet faces? How would I do this?

Thank you

Jim January 30, 2008 15:21

Re: Calculating Pressure Drop
 
STAR-CCM+ or STAR-CD?

M January 30, 2008 17:26

Re: Calculating Pressure Drop
 
Sorry, Star-CD.

Kasper January 31, 2008 06:56

Re: Calculating Pressure Drop
 
You will find this macro useful (It looks better if I email it to you)

!************************************************* * ! FLS Airtech ! Case study of pressure drop across filter section ! Pressure drop calculations ! KSK, FLS Airtech, Aug. 2005. !*************************************************

load$

!----finds the total massflux through the inlet------------

!----Defines the inlet boundary

cset news grange -0.1 2.25

cset subs type 4

spoi 0 1.5 3

snor 0 0 -1

surf off

view -1 -0.95 -0.44 $zoom,off

cplo

!----the density is loaded into post register 4

getc all dens

!----integrates over the defined inlet plane

inte cset

!---gets the total massflux (tavs multiplies the A*v_n*scalar in postregister 4)

*get mtot tavs

!----Finds the total pressure------------------------------

!Section: Inlet.

cset news type 4

spoi 0 1.5 3

snor 0 0 -1

surf off

view -1 -0.95 -0.44 $zoom,off

cplo

getc,all,dens

!----stores the total pressure in register 5

oper,getc,ptot,5

!---- multiply the density and total pressure

oper,mult,4,5,4

inte cset

*get avtp tavs

*set TP0 avtp / mtot

!Section: Outlet.

cset news grange 17.6,

spoi 20 1.405 -2.5 1

snor 0 0 -1

surf off

view -1 -0.95 -0.44

cplo

getc,all,dens

oper,getc,ptot,5

oper,mult,4,5,4

inte cset

*get avtp tavs

*set TP1 avtp / mtot

!Pressure difference over the inlet-outlet sections

*set dp-filter TP1 - TP0

*list


Andrea January 31, 2008 15:08

Re: Calculating Pressure Drop
 
Drop a .pstt file from the sim at each time step you want to know the pressure...
Then cset,news,type,n where n is the type of the cell at your inlet (or outlet) and then store the pressure data in your model
After that do summa,cset and in the text windows you'll se the mean pressure stored in the register 4

Pauli January 31, 2008 15:31

Re: Calculating Pressure Drop
 
Boundary region monitoring.

At the command line type - help brmo.

In the NavCenter go to Analysis Controls -> Output Controls -> Monitor Engineering Behavior -> Monitor Boundary Behavior.

M January 31, 2008 18:06

Re: Calculating Pressure Drop
 
Pauli,

That was what I tried to do before I posted this message but I can't seem to find where the data is output to? I've tried both the standard and additional .info files.

Polly Eda February 1, 2008 08:41

Re: Calculating Pressure Drop
 
Try the .erd file.


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