Urgent Help: Surface Wrapper & Contact Prevention (Crashes using more than one CP)

AndreP · July 31, 2018, 08:44

Hello Guys,

I'm a master student of Motorsport Engineering and I'm currently in the last part of my dissertation studying the Aerodynamic Impacts of the Halo in a Formula One car.

I'm currently trying to mesh and run simulations on the Perrinn Formula 1 car, so then I can put the standard Halo and different Halo geometries I created to study their influences and try to reduce the impact of the Halo in the car.

However, I'm having some problems. I tried to mesh the car using only the Surface Remesher, but I started having too many errors on the surface (The original CAD is not mine, so I don't have a lot of freedom to change it), so I opted to go with Surface Wrapper.

After doing the first mesh sucessfully, I found that the CAD was too detailed (5M cells JUST in surface mesh), and then I started simplifying the car, but now I'm having problems applying the Surface Mesh.

If I try to mesh the car WITHOUT contact prevention, it meshes alright and the surface mesh doesn't show a lot of problems, but when I try to apply some contact preventions is where the nightmare beggins. If I apply just one contact prevention, it works fine and meshes in 20min. If I try to apply more than one contact prevention, it just loops in the "Performing Contact Prevention" and then crashes without memory. I though it could be one of the contact preventions that was crashed, but the mesh without contact prevention seems ok, so I don't think it can be this!

I tried to find anything online, tried a lot of different combinations and nothing seems to work!

Could ANYONE please help me with this? My dissertation is basically stuck, which is getting alarming to me!

Here is the file in case someone can have a look, which is obviously easier than just reading my text!

https://drive.google.com/file/d/1Ftz...ew?usp=sharing

Thank you! If you need any further information, please don't hesitate to ask! I'll be coming back here every hour!

AndreP · July 31, 2018, 08:47

On the link I shared above, there are 4 contact preventions. If you turn them off, you'll be able to do the Surface Mesh, but as soon as I turn on MORE than one, it just stucks there until it crashes!

I tried to mesh seperatedly with the 4 contact preventions (1 at the time) and all the 4 meshed! It's really when I add more than one!

Be carefull, don't try to do Volume Mesh unless you're runing in a Cluster, as I'm expecting something above 40M volume cells on that, and if you're running it on a Laptop or normal computer, probably it'll suck all your memory and crash! Just mesh the Surface Mesh (around 2M)

AndreP · July 31, 2018, 09:31

I can have the mesh with roughly good quality without contact prevention, but this increases the number of cells, which will be huge when I do volume mesh, so I'm trying to only refine the zones I really need!

AndreP · July 31, 2018, 13:14

It's strange that now, that I've switch to a Region Based Mesh (RBM) from a Parts Based Mesh (PBM), the Contact Prevention is now working and allows me to have more than one? What could be causing this?

To change from PBM to RBM I didn't started from scratch, I just deleted the Regions, the Operations and maintained all the parts! What could be the cause of the problem of the Contact Prevention in the PBM operation?

AndreP · August 1, 2018, 07:36

I know sometimes it's hard and boring to keep up with some of us, new arrivals here to the forum, with dumb and basic questions, that doesn't even bother doing some research first.

I'm a masters student, so if I get to the point of coming here to ask a question is because I already used all the research I could to find my problem, including Help files and everything! So if anyone has any hint or if anyone has ever this happened to him, it would be of major help!

SoAero · August 1, 2018, 23:30

What’s the floor set to on your contact prevention controls? It defaults to 1e-07 and that super small size is consistent with over refinement. Over refinement could cause your machine to run out of memory.

AndreP · August 2, 2018, 07:56

Quote:

Originally Posted by SoAero

What’s the floor set to on your contact prevention controls? It defaults to 1e-07 and that super small size is consistent with over refinement. Over refinement could cause your machine to run out of memory.

You are probably right. Because I always used RBM and in RBM you have to assign the value, which I normaly use 0.001m, and in PBM he automatically assign the 1e-07, and I didn't changed that! That could be very well the problem here! Thank you for the hint! Although now I'm already running the RBM I'll try to go back one day to the PBM and try to change that to see if it runs! Thank you!

AndreP · August 2, 2018, 08:04

Didn't even took that long. Yes, it was exactly that problem! Thank you for the hint!

Reduced the contact prevention to 0.001 and it went by pretty quick! Thank you man!

Will leave here some "search related google searches" for anyone having the same problem!

" contact prevention crash error loop memory "

July 31, 2018, 08:44	Urgent Help: Surface Wrapper & Contact Prevention (Crashes using more than one CP)	#1
AndreP Member André Pinto Join Date: Oct 2017 Location: Brussels, Belgium Posts: 84 Rep Power: 9	Hello Guys, I'm a master student of Motorsport Engineering and I'm currently in the last part of my dissertation studying the Aerodynamic Impacts of the Halo in a Formula One car. I'm currently trying to mesh and run simulations on the Perrinn Formula 1 car, so then I can put the standard Halo and different Halo geometries I created to study their influences and try to reduce the impact of the Halo in the car. However, I'm having some problems. I tried to mesh the car using only the Surface Remesher, but I started having too many errors on the surface (The original CAD is not mine, so I don't have a lot of freedom to change it), so I opted to go with Surface Wrapper. After doing the first mesh sucessfully, I found that the CAD was too detailed (5M cells JUST in surface mesh), and then I started simplifying the car, but now I'm having problems applying the Surface Mesh. If I try to mesh the car WITHOUT contact prevention, it meshes alright and the surface mesh doesn't show a lot of problems, but when I try to apply some contact preventions is where the nightmare beggins. If I apply just one contact prevention, it works fine and meshes in 20min. If I try to apply more than one contact prevention, it just loops in the "Performing Contact Prevention" and then crashes without memory. I though it could be one of the contact preventions that was crashed, but the mesh without contact prevention seems ok, so I don't think it can be this! I tried to find anything online, tried a lot of different combinations and nothing seems to work! Could ANYONE please help me with this? My dissertation is basically stuck, which is getting alarming to me! Here is the file in case someone can have a look, which is obviously easier than just reading my text! https://drive.google.com/file/d/1Ftz...ew?usp=sharing Thank you! If you need any further information, please don't hesitate to ask! I'll be coming back here every hour!

August 1, 2018, 23:30		#6
SoAero New Member Owen Join Date: Aug 2018 Posts: 20 Rep Power: 8	What’s the floor set to on your contact prevention controls? It defaults to 1e-07 and that super small size is consistent with over refinement. Over refinement could cause your machine to run out of memory. granzer likes this.

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July 31, 2018, 08:47		#2
AndreP Member André Pinto Join Date: Oct 2017 Location: Brussels, Belgium Posts: 84 Rep Power: 9	On the link I shared above, there are 4 contact preventions. If you turn them off, you'll be able to do the Surface Mesh, but as soon as I turn on MORE than one, it just stucks there until it crashes! I tried to mesh seperatedly with the 4 contact preventions (1 at the time) and all the 4 meshed! It's really when I add more than one! Be carefull, don't try to do Volume Mesh unless you're runing in a Cluster, as I'm expecting something above 40M volume cells on that, and if you're running it on a Laptop or normal computer, probably it'll suck all your memory and crash! Just mesh the Surface Mesh (around 2M)

July 31, 2018, 09:31		#3
AndreP Member André Pinto Join Date: Oct 2017 Location: Brussels, Belgium Posts: 84 Rep Power: 9	I can have the mesh with roughly good quality without contact prevention, but this increases the number of cells, which will be huge when I do volume mesh, so I'm trying to only refine the zones I really need!

July 31, 2018, 13:14		#4
AndreP Member André Pinto Join Date: Oct 2017 Location: Brussels, Belgium Posts: 84 Rep Power: 9	It's strange that now, that I've switch to a Region Based Mesh (RBM) from a Parts Based Mesh (PBM), the Contact Prevention is now working and allows me to have more than one? What could be causing this? To change from PBM to RBM I didn't started from scratch, I just deleted the Regions, the Operations and maintained all the parts! What could be the cause of the problem of the Contact Prevention in the PBM operation?

August 1, 2018, 07:36		#5
AndreP Member André Pinto Join Date: Oct 2017 Location: Brussels, Belgium Posts: 84 Rep Power: 9	I know sometimes it's hard and boring to keep up with some of us, new arrivals here to the forum, with dumb and basic questions, that doesn't even bother doing some research first. I'm a masters student, so if I get to the point of coming here to ask a question is because I already used all the research I could to find my problem, including Help files and everything! So if anyone has any hint or if anyone has ever this happened to him, it would be of major help!

August 2, 2018, 08:04		#8
AndreP Member André Pinto Join Date: Oct 2017 Location: Brussels, Belgium Posts: 84 Rep Power: 9	Didn't even took that long. Yes, it was exactly that problem! Thank you for the hint! Reduced the contact prevention to 0.001 and it went by pretty quick! Thank you man! Will leave here some "search related google searches" for anyone having the same problem! " contact prevention crash error loop memory "