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-   -   Water Hammer simulation in Open Foam (http://www.cfd-online.com/Forums/openfoam/113036-water-hammer-simulation-open-foam.html)

simin_ds February 11, 2013 03:06

Water Hammer simulation in Open Foam
 
Hi every one

I am going to simulate water hammer phenomenon in a pipe using open foam as a simple case. but I have problem to set the boundary conditions. has any one simulated this phenomenon before. I need to know the settings which is required.:confused:

thanks in advance.
Simin

nimasam February 11, 2013 16:33

Hello Dear simin
your question is too much general, you said:
Quote:

I have problem to set the boundary conditions
whats your problem?
forexample do you know the velocity at inlet? if yes, then put your velocity fixedValue
or for wall is it no slip condition? then velocity would be zero and etc
so i think its better you make it clear where is the problem :)
However, if you want to find appropriate setting for your simulation, i suggest you to search in articles, then for those configuration, you can find similar BC at OpenFOAM

simin_ds February 11, 2013 16:51

Hi nima

thank you for your reply.
I do not have problem for boundary conditions but in order to simulate the problem the density variation using the module of elasticity,K=dP/drho/rho, should be set to show the pressure change and compresibility. I simulate water hammer by fluent before using udf, but in open foam i do not know where I can set this change.
Hope I could explain my question clear. :)

nimasam February 11, 2013 17:05

first of All, as it a pressure shock, compressible flow u should use a compressible isothermal solver, which solver did you choose?

vatavuk February 13, 2013 06:42

Hi Simin,
In the section 3.4 of the Programmers Guide you will find a tutorial of a water hammer simulation. The files of this tutorial can be found in the folder .../tutorials/compressible/sonicLiquidFoam.

I tried this tutorial some time ago and modified it to get the transient flow in a pipe resulting from the sudden opening of a valve. The pressure decrease was correct according to the Joukowski theory but instead of a sharp decrease of pressure there was a smooth profile that suggests there was strong false diffusion in the results. Were you able to get good results with fluent?

Best Regards,
Paulo

simin_ds July 5, 2013 04:44

hi vatavuk

thank you for conducting me. yes I got good results with fluent. I think for Open foam you should select smaller delta t to get the good results I had this problem with fluent but after selecting smaller delta T I got very good results.

Chris Lucas July 9, 2013 03:03

Hi,

if you need compressible water properties in openfoam have a look at

http://www.cfd-online.com/Forums/ope...roperties.html

Kind regards,
Christian

jgv July 12, 2013 10:25

Column separation/rejoining triggered water hammer
 
Interesting discussion above. I am a novice user in OpenFOAM, and I am interested in knowing whether someone has been able to simulate episodes of water hammer involving the formation of cavitation pockets followed by the collapse of these pockets (column rejoining). It is a well-studied phenomena, but most references to this appear in unsteady 1D flow pipe solvers. Thank you in advance for the reply.

vatavuk July 13, 2013 08:39

Hi Jose,
And welcome to the forum!
I have an impression that water hammer simulation with CFD is still in the beginning, it seems it hasn’t been established yet that that CFD can perform reliable simulations for more simple one phase flows.
Best Regards,
Paulo

mhd.abdo January 7, 2014 02:00

Interesting discussion..
may i didn't professional english :)
am also going to simulate water hammer in pipe line using ansys cfx
i start with single pipe modle i make inlet as opning and outlet as mass flow rate and wall no slip wall .. for fluid islect just water as constant pro...
and ididn't know is this is ok or not also for the time step is there any way to calculate it ...
ineed the guideline for that or any helpfull refreances plz ....

samirtala April 16, 2015 01:12

water hammer
 
How can I simulate water hammer in pipes

mhd.abdo April 17, 2015 15:48

Dear samirtala
It's very easy to do that if u use ansys program
but need frist to describe model and the boundary conditions


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