[hamidciv]

hi every body
i used ansys version 14, in fluid settings tab in cartesian velocity components, u,v,w On what basis spicified? i using free surface and cartesian system and i have two phase consist of water & air, i have depth and velocity in inlet from experimental data, but i dont know exact velocity components, whether I can put it on automatic setting and What is your suggestion?
please help me
thanks a lot

[ghorrocks]

You have to apply boundary conditions at locations where you know the flow conditions. If you do not know the flow conditions then you cannot apply boundary conditions.

But can't you guess that the flow direction is normal to the boundary? This is the normal approach.

[hamidciv]

hi dear glenn
If my guess with the actual values have big difference, How much effected on my results? Do you think if I put it on automatic setting Is not better?
slope of chutes is 17 degree, horizontial length is :53 m,
velocity inlet is:25m/s , depth inlet :1 m
please tell me your opinion, thanks a lot for help me

[ghorrocks]

If my guess with the actual values have big difference, How much effected on my results?

I will let you answer that question .

Do you think if I put it on automatic setting Is not better?

Automatic setting of what?

My opinion of the model you show is that you are unlikely to get that to converge as the down stream boundary is likely to be in the region where the flow is still recovering from the hump. You are going to have to move the downstream boundary further downstream. If you know the depth and velocity at the inlet it should be OK.

[hamidciv]

dear glenn
thanks a lot for spending time for me, my mean of settings is two method that i can considered, As you know cartesian velocity components is
Adjustable in 2 modes are automatic with value & automatic, my mean is when i dont know exat value of u , v ,w , is not better i using automatic.

i have normal speed & velocity in inlet
thanks a lot dear glenn.

[ghorrocks]

Automatic with value uses an initial condition if one is provided, otherwise the specified value. Automatic just uses an initial condition if one is provided, otherwise the global initial condition.

If this is for an initial condition then you can often use a guess as the flow will generate the flow soon enough.

[hamidciv]

dear glenn, thanks a lot for help me