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OpenFOAM - How to simulate wall-wall contact of rigid body motion

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Old   June 19, 2019, 03:52
Default OpenFOAM - How to simulate wall-wall contact of rigid body motion
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Hi, formers.

I am using OpenFOAM to simulate a case of geyser erupting from an underground pipe. InterFoam is used as the solver. The case setup is simple with a horizontal pipe and a riser at the middle of the pipe, and described as below:

At the horizontal pipe, its downstream end is an solid wall with an air pocket of a specific length, and its upstream end is a pressure inlet with a specific pressure head. At the top of the riser, it acts as pressure outlet with a specific pressure to prescribe an initial water level at the riser. In the simulation, the air pocket initially at the downstream end will move towards upstream, and some air will move upwards at the riser. Under some conditions, geyser will happen to break through the prescribed water level at the riser.

I have done the simulation, but Next is the CHALLENGE to me. I am going to look at the situation whether the geyser (like a high-velocity jet) can lift up a metal riser cover and how far it is. The simulation requires a rigid body with a motion induced by flow. I use rigidBodyMotion as the motion solver to simulate the movement of the riser cover.

What is the CHALLENGE to me?? It is how to simulate the cover sitting on ground in OF. I found that it is very difficult to do such wall-wall contact. See the attached picture. The followings are two fail approaches:

1. I used interDyMFoam to do the simulation. The cover is initially in the air and falls to sit with its edges on the ground. The simulation crashes since the meshes are getting thinner and thinner near the wall-wall contact. Too much mesh distort seems the reason of model crash.

2. To avoid such wall-wall contact, I tried to use overset grid method, which is overInterDyMFoam. Again, the cover is initially in the air and falls to sit with its edges on the ground. After some time, the cover intrudes into the ground, instead of sitting on ground.

I have already dragged on this problem for some time. Can any experts here give me some guidance?
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Old   June 19, 2019, 17:10
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Hi, though not totally sure, I think the ACMI is what you need. I did a solid-solid rotating simulation with ACMI. Check the tutorial of ACMI come with openfoam, hope you find something useful.


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Originally Posted by foamF View Post
Hi, formers.

I am using OpenFOAM to simulate a case of geyser erupting from an underground pipe. InterFoam is used as the solver. The case setup is simple with a horizontal pipe and a riser at the middle of the pipe, and described as below:

At the horizontal pipe, its downstream end is an solid wall with an air pocket of a specific length, and its upstream end is a pressure inlet with a specific pressure head. At the top of the riser, it acts as pressure outlet with a specific pressure to prescribe an initial water level at the riser. In the simulation, the air pocket initially at the downstream end will move towards upstream, and some air will move upwards at the riser. Under some conditions, geyser will happen to break through the prescribed water level at the riser.

I have done the simulation, but Next is the CHALLENGE to me. I am going to look at the situation whether the geyser (like a high-velocity jet) can lift up a metal riser cover and how far it is. The simulation requires a rigid body with a motion induced by flow. I use rigidBodyMotion as the motion solver to simulate the movement of the riser cover.

What is the CHALLENGE to me?? It is how to simulate the cover sitting on ground in OF. I found that it is very difficult to do such wall-wall contact. See the attached picture. The followings are two fail approaches:

1. I used interDyMFoam to do the simulation. The cover is initially in the air and falls to sit with its edges on the ground. The simulation crashes since the meshes are getting thinner and thinner near the wall-wall contact. Too much mesh distort seems the reason of model crash.

2. To avoid such wall-wall contact, I tried to use overset grid method, which is overInterDyMFoam. Again, the cover is initially in the air and falls to sit with its edges on the ground. After some time, the cover intrudes into the ground, instead of sitting on ground.

I have already dragged on this problem for some time. Can any experts here give me some guidance?
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Old   June 20, 2019, 02:12
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Based on my understanding, ACMI is used to couple patches partially overlapped. It is commonly applied for the rigid body with prescribed motions.

It appears not working in my case with flow induced motion.

Anything I miss?
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Old   June 20, 2019, 05:37
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As I mentioned in my original post, I think that overset grid technique may be a solution to my case.

But, when the riser cover falls down and approaches the ground (i.e. top of riser), the meshes of cover get intruding into the riser. It means that when a solid wall in one overset layer contacts a solid wall in another overset layer, they does not interact with each other.

Any expert can tell whether this is correct in OF? (remark: I use OF v1712) Or, it is just some incorrect setting in my case setup?
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