Hi everyone,
I am working on a curved domain in which a ship is situated in the middle (geometry is given below). In my understanding the general fluid flow is parallel to the x axis from inlet to outlet. How can I change the flow direction parallel to my domain boundary by using velocity and components?
And how can I avoid the possible reflections on the bends?
Howdy Anagha R H,
This seems too simple because a change of your Vx to -Vx will reverse the flow. The sign/direction is arbitrary. But I worry.
You show Cartesian coordinates, but it seems polar coordinates of radial and circumferential values would be better. Further, secondary flow would appear in a real case because of drag. Fluid at the channel bottom is slowed and the pressure at the wall to curve the flow is less than at the surface. There is a circulation driven by this difference, down the outer channel wall, inward at the bottom, then upward and outward at the surface. Your flow is not quite parallel to your x coordinate.
As for reflections at the bends,waves reflect but flow does not. So unless the flow velocity changes, there should be no "reflection."
However, I'm not confident I have addressed your concerns.
Happy Trails
Len
Hi Leonard, How are you?
Thank you very much for the reply. But I think I didn't covey my problem properly.
I am simulating that curved domain for a ship flow in a canal. The velocity I have given is in negative x direction due to the position of the ship. I have applied damping and forcing in the outlet region to prevent backflow yet getting the reversed flow from the start of the simulation itself. I think the reversed flow is due to the bend of the canal since I have done this for a straight canal and that runs okay. So I am thinking about giving the velocity parallel to my curved domain. But I don't know how to give the velocity as components or its the right way to eliminate the reversed flow. The reflections are always shows on the outlet as the DFBI is released even though I am using flat VOF wave.
Software using - STARCCM+
Howdy Anagha R H,
In my answer to your previous question: “Reversed flow at outlet due to the release of DFBI?” I offered a possible solution to reflections:
“It may also work to prevent the wave due to the DFBI release by removing the same volume of canal fluid simultaneously, that is to exchange volumes so there is no excess to trigger a wave.”
I read up on a “flat VOF wave” and did not see what it has to do with the volume disturbance caused by injecting DBFI, which disturbance is reflecting at your channel ends in my view. The programming options are new to me after 40 years, so I may be missing something there, but raindrops caused ripples on a pond long before computer simulations.
Your focus on the bend for reflections may be valid, but not the channel walls themselves as reflectors. The secondary flow they cause may be the problem.
I worry about how well this worked in a straight channel, but I expect that the fancy algorithms that handle forcing and damping work better there. With curvature and resulting secondary flow their requirements may be violated.
Remember that you are working in Fluid Dynamics, and flows can be seriously nonlinear. The fluid / flow knows how to handle any case, but your program may not.
Let’s try again if needed, it is an interesting problem.
Happy Trails,
Len
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