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max September 21, 2002 07:15

water jet
 
I want to simulate a high-velocity free water jet in the air and to find the track of the water.The air was supposed to static,and gravity was considered.Could anyone give me some advice on how to specify the B.C. Thanks in anvance!

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|__ |?wall?pres outet?

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?wall?pres outlet?

sri September 21, 2002 15:17

Re: water jet
 
Hi,

The following procedure might help you :

1)Let us take the domain shape a rectangle.

2)Make a small opening at the left edge,this can be acomplished by splitting the whole edge in Gambit.

3)Velocity inlet bc is given to this.

4)The right edge is given wall bc.

5)Fix the values of velocities of fluid zone(air) through

define--->boundary conditions--->fluid/fix values.

6)Multiphase model should be used.

hope this helps you!

You can model a moving jet using MDM feature,if interested.

Regards, sri

max September 21, 2002 22:47

Re: water jet
 
Hi,sri Thanks for your help. And my question is what kind of B.C should be applied to the bottom.(wall? pres out?).


sri September 22, 2002 03:00

Re: water jet
 
wall,

regards, sri

max September 22, 2002 04:42

Re: water jet
 
thanks! The question is just like a high-velocity water enter a wall-bounded room?

max September 24, 2002 22:55

Re: water jet
 
I applied the B.C. as discussed above,however,it seemed difficult to converge.

Alamgir September 26, 2002 01:57

Re: water jet
 
r u running k-e model? if so then just have a look to under relaxation factor, u should run with low urf, make it half, then iterate.

Alamgir

max September 27, 2002 21:19

Re: water jet
 
Thanks,Alamgir! Do u think it was a static problem or a transient one?

shin October 7, 2002 10:45

Re: water jet
 
are you using a multiphase flow model to solve your problem?if so, which model are you using,VOF or Mixture?i also want to know how do you handle the B.C. because i am trying to solve a similar question:a high tempreture and pressure gas jet ejecting from a Laval nozzle under water.i hope your responses.thanks in advance.

max October 8, 2002 04:14

Re: water jet
 
Hi, shin The VOF scheme was used and wall B.C. was applied at the outer surface, however, it was difficult to converge. What about your question? I had simulated a steam-jet ejector, something like a Laval nozzle with a second throat. However, it was compressible and wall bounded. I had a foolish question: If I applied the Boundary conditions described above, that is, a high-velocity water jetting in a wall-bounded space, and no outlet B.C was applied, will the water become more and more in the space?

Alamgir October 8, 2002 06:50

Re: water jet
 
Static or transient, both needs low urf to converge, otherwise continuity (residual) will touch the top.

bye

Alamgir

shin October 13, 2002 11:32

Re: water jet
 
hi,max.i have a same feeling as your,the iteration is difficult to converge.by the way,i want to ask you a question,namely did you solve the problem of the steam-jet ejector,and which fluid the jet was ejected in.my problem is not same as your:the external water flow is infinite, but i think the wall B.C. is right.

max October 16, 2002 21:19

Re: water jet
 
Hi,shin super-heated steam was used in my previous case.and now i am simulating a high-velocity water jettting in infintite atmosphere,can you give me some advice?


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