[enass massoud]

What do you mean by moving geometry in the first quadrant?

[chikko04]

Originally Posted by enass massoud

What do you mean by moving geometry in the first quadrant?

I mean that all 4 vertices of our rectangle must be in first quadrant far away from the axis. For example, use these coordinates for the vertices:

A(4,4); B(5,4); C(4,14); D(5,14).

And, because of the radius is 0.5, now you can choose any edge to be an axis.
Now the amg errors should be gone.

[enass massoud]

Now when you did so you obtained different results?

[chikko04]

Originally Posted by enass massoud

Now when you did so you obtained different results?

Yes, i did. I obtained that i already describe a few posts ago.

[enass massoud]

But when i simulated the horizontal case just as I described above i obtained same results as tutorial.. Why when i do vertical case in xy positive quadrant it gave same results as horizontal??

[chikko04]

Originally Posted by enass massoud

But when i simulated the horizontal case just as I described above i obtained same results as tutorial.. Why when i do vertical case in xy positive quadrant it gave same results as horizontal??

I don't follow you... You had sim a vertical pipe, right? And you had an error, the amg error, is it right? To solve that error try to move geometry how i have already written, and see if you solve the error! Run the sim, and please, tell me your results, maybe am i in error during setup.

[enass massoud]

I received no error when i placed pipe lying horiZontal and enable gravity in -x

[chikko04]

Originally Posted by enass massoud

I received no error when i placed pipe lying horiZontal and enable gravity in -x

The errors occours if you place the axis along the x=0 axis!

[enass massoud]

refer to your inbox please

[LuckyTran]

Originally Posted by chikko04

update:
thinking better about what have you written, i think that my first thought was right. Gravity act over all domain, and if it is constant nothing should be change in the solution if you consider the developed flow shape ( not values).

For fully developed, incompressible, constant property flows in straight pipes, the driving pressure gradient acts exactly like a body force. This is why you are able to use a streamwise periodic boundary condition. You will find that the velocity profile is exactly the same for these two cases.

For developing flows it is also similar, though not exactly. In the Blasius-type boundary layer equations the influence of pressure is reduced to a constant pressure gradient (and if the gradient is a constant, then it also acts like a constant body force). So local pressure distribution would be a higher order effect.

[enass massoud]

Originally Posted by LuckyTran

For fully developed, incompressible, constant property flows in straight pipes, the driving pressure gradient acts exactly like a body force. This is why you are able to use a streamwise periodic boundary condition. You will find that the velocity profile is exactly the same for these two cases.

For developing flows it is also similar, though not exactly. In the Blasius-type boundary layer equations the influence of pressure is reduced to a constant pressure gradient (and if the gradient is a constant, then it also acts like a constant body force). So local pressure distribution would be a higher order effect.

I am really confused. For horizontal case i had no problems. For vertical case i draw same geometry and i enabled gravity in -x direction. The radial velocity is given instead of axial in horizontal case. I received reversed flow and the flow is not developed?

[chikko04]

Originally Posted by LuckyTran

For fully developed, incompressible, constant property flows in straight pipes, the driving pressure gradient acts exactly like a body force. This is why you are able to use a streamwise periodic boundary condition. You will find that the velocity profile is exactly the same for these two cases.

For developing flows it is also similar, though not exactly. In the Blasius-type boundary layer equations the influence of pressure is reduced to a constant pressure gradient (and if the gradient is a constant, then it also acts like a constant body force). So local pressure distribution would be a higher order effect.

Another question, why if i place a vertical pipe, with edges in the first quadrant, but far away from the origin of the axes, i had a solution different from the horizontal case?

[enass massoud]

I totally agree with LuckyTran cause I performed all theoretical calculations for both geometry the velocity profile, pressure drop n skin friction coefficient should all be same. I did both cases as plannar and results emphasis that. as i said earlier my problem is in simulating axisymmetric vertical pipe.

[enass massoud]

LuckyTran can you advise me here please. I made horizontal pipe 2D with centerline being on x axis. I then enabled gravity in -x direction. The inlet boundary condition is specified to inlet with radial velocity component. I think now fluent understands it as vertical upward flow. I then run case and I received reversed flow in solution panel and flow is not developed?? Any suggestions??