[simin_ds]

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.

thanks in advance.
Simin

[nimasam]

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

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]

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]

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

[vatavuk]

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]

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]

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]

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]

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]

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]

How can I simulate water hammer in pipes

[mhd.abdo]

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

[AliMostafa]

Originally Posted by simin_ds

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.

Hi Simin
I was searching for water hammer simulation in fluent and saw your post on CFD Forum. You said "I simulate water hammer by fluent before using udf".
How you simulated water hammer by fluent? Have you any manual or manuscript? I really appreciated if you help me.
Thank you very much.

[rahulgarg]

how can i simulate a simple water hammer problem in a pipe with the help of HAMMER software.

[Ramin HN]

Hi Simin,
I want to simulate water hammer by FLUENT.Could you say how I can do it...
I realy dont have enough time.
Thanks.