Week 4 Challenge : CFD Meshing for BMW car
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Ansa Project BMW meshing
This is a BMW car model, where we need to do surface mesh of the car body.
TOPO (Topo > Faces > Topo) – In starting, it was seen that, there are multiple of single coons present in the car body. So, we have done topo cleanup process to remove these unwanted single coons.
Fine (Topo > Auxiliaries > Fine)– It was seen that, the car body outer surface is not uniform, so we will be using ‘fine’ option to make the car surface uniform. But it is too difficult for us to make the car model uniform by using ‘fine’ option.
Length (Mesh > Perimeters > Length) (Perimeters & Coons)– To get out from the limitation of use of the ‘fine’ option, we will use ‘length’ option in the ‘mesh’ parameters. In ‘length’ we have defined the ‘perimeter’ & ‘coon’ size to the minimum, so that the whole car body will be seen uniformed.
Note: As there is a feature of ansa that, we can develop a symmetrical body on the opposite side of the body. If there is only having single body. So, we will delete the other half portion of the car body, and perform all the 2D meshing & volumetric mesh on the half portion of the body, and then mirror this body.
After deleting half portion of the car body, we will delete all the unwanted portion of the car, which is held inside the car body, because we don’t care about the portion inside the body, but outer body should be clear & having full surface.
Paste (Topo > Coons > Paste): When there are two coons, which are too much close to each other, then we can use paste option to join two single coons. For paste option, you have to select both the coons and then middle click to full fill the task.
Extend (Topo > Faces > Extend) – When there are two coons are mating each other, even though they were showing in the form of single coons. And not able to resolve the issue from the ‘Topo’ action. Then we can use extend option, so that the surface which is having single coons and positioned little bit far away from any other surface.
Intersect (Topo > Faces > Intersect) – When there are two surfaces, which were not showing any double coon or triple coons, then we have to intersect both the surface. For this we have to use Intersect option. And select both the mating surfaces with each other, which were seems to be shown intersected.
Cons2curves (Topo > Curves > Cons2curves) – When there are surface which were showing too much glitches, and shown too much intersected with each other, then we have to delete all the available surfaces. If we delete all the surface, then it will be very difficult to retrieve all the surface back. Then cons2curves option can be used. For this we have to select the outer coons of that surface before deleting the surface. SO that we can use that coons to generate new surfaces.
After deleting all the overlapped surface & solve all the single & triple coons. Then we can approach to the PID selection. For PID selection we have to remove all the unwanted PID with the help of compress option. So that all the unwanted PID can be selected.
LOGO PID : For logo PID, we have removed all the single coons, and make LOGO a single entity. LOGO PID need to be mesh with the mesh length of 1 mm. And we have set min & max length of 0.4 to 2 mm. Some other quality criteria also defined for better mesh generation. Mesh quality was ‘Tria’ as recommended. After performing the mesh generation, the LOGO. We have seen some quality errors like skewness & min length. There are some off elements found after mesh generation.
Re construct (Mesh > Shell Mesh > Re-construct) – To minimize the off elements, we have used Re-construct option for the visible PID. Even after re-construct there were some off elements were present in the mesh. To remove remaining off elements.
Move (Mesh > Grid > Move) – To remove remaining off elements, there were different ways to do this. Like Cut option, we can check the area of off elements and remove all the unnecessary cuts to remove off elements & and move option is equal helpful to remove off element. Select the hot point of the off element and try to move it till it is showing off elements meshed, then set the hot point.
Grid PID - For Grid PID, we have removed all the single coons, and make grid a single entity. Grid PID need to be mesh with the mesh length of 1 mm. And we have set min & max length of 0.3 to 2 mm. Some other quality criteria also defined for better mesh generation. Mesh quality was ‘Tria’ as recommended. After performing the mesh generation, the Grid. We have seen some quality errors like skewness & min length. There are some off elements found after mesh generation.
Re construct (Mesh > Shell Mesh > Re-construct) – To minimize the off elements, we have used Re-construct option for the visible PID. Even after re-construct there were some off elements were present in the mesh. To remove remaining off elements.
Move (Mesh > Grid > Move) – To remove remaining off elements, there were different ways to do this. Like Cut option, we can check the area of off elements and remove all the unnecessary cuts to remove off elements & and move option is equal helpful to remove off element. Select the hot point of the off element and try to move it till it is showing off elements meshed, then set the hot point.
Rear view mirror PID - For Rear view mirror PID, we have removed all the single coons, and make grid a single entity. Grid PID need to be mesh with the mesh length of 2 mm. And we have set min & max length of 1 to 3 mm. Some other quality criteria also defined for better mesh generation. Mesh quality was ‘Tria’ as recommended. After performing the mesh generation. We have seen some quality errors like skewness & min length. There are some off elements found after mesh generation.
Re construct (Mesh > Shell Mesh > Re-construct) – To minimize the off elements, we have used Re-construct option for the visible PID. Even after re-construct there were some off elements were present in the mesh. To remove remaining off elements.
Move (Mesh > Grid > Move) – To remove remaining off elements, there were different ways to do this. Like Cut option, we can check the area of off elements and remove all the unnecessary cuts to remove off elements & and move option is equal helpful to remove off element. Select the hot point of the off element and try to move it till it is showing off elements meshed, then set the hot point.
Window PID - For Rear view mirror PID, we have removed all the single coons, and make grid a single entity. Window PID need to be mesh with the mesh length of 2 mm. And we have set min & max length of 1 to 3 mm. Some other quality criteria also defined for better mesh generation. Mesh quality was ‘Tria’ as recommended. After performing the mesh generation. We have seen some quality errors like skewness & min length. There are some off elements found after mesh generation.
Re construct (Mesh > Shell Mesh > Re-construct) – To minimize the off elements, we have used Re-construct option for the visible PID. Even after re-construct there were some off elements were present in the mesh. To remove remaining off elements.
Move (Mesh > Grid > Move) – To remove remaining off elements, there were different ways to do this. Like Cut option, we can check the area of off elements and remove all the unnecessary cuts to remove off elements & and move option is equal helpful to remove off element. Select the hot point of the off element and try to move it till it is showing off elements meshed, then set the hot point.
Lights PID - For Lights PID, we have removed all the single coons, and make grid a single entity. Lights PID need to be mesh with the mesh length of 4 mm. And we have set min & max length of 1 to 5 mm. Some other quality criteria also defined for better mesh generation. Mesh quality was ‘Tria’ as recommended. After performing the mesh generation. We have seen some quality errors like skewness & min length. There are some off elements found after mesh generation.
Re construct (Mesh > Shell Mesh > Re-construct) – To minimize the off elements, we have used Re-construct option for the visible PID. Even after re-construct there were some off elements were present in the mesh. To remove remaining off elements.
Move (Mesh > Grid > Move) – To remove remaining off elements, there were different ways to do this. Like Cut option, we can check the area of off elements and remove all the unnecessary cuts to remove off elements & and move option is equal helpful to remove off element. Select the hot point of the off element and try to move it till it is showing off elements meshed, then set the hot point.
Silencer PID - For Silencer PID, we have removed all the single coons, and make grid a single entity. Lights PID need to be mesh with the mesh length of 3 mm. And we have set min & max length of 1 to 5 mm. Some other quality criteria also defined for better mesh generation. Mesh quality was ‘Tria’ as recommended. After performing the mesh generation. We have seen some quality errors like skewness & min length. There are some off elements found after mesh generation.
Re construct (Mesh > Shell Mesh > Re-construct) – To minimize the off elements, we have used Re-construct option for the visible PID. Even after re-construct there were some off elements were present in the mesh. To remove remaining off elements.
Move (Mesh > Grid > Move) – To remove remaining off elements, there were different ways to do this. Like Cut option, we can check the area of off elements and remove all the unnecessary cuts to remove off elements & and move option is equal helpful to remove off element. Select the hot point of the off element and try to move it till it is showing off elements meshed, then set the hot point.
Rims & Tires PID - For Rimes & Tires PID, we have removed all the single coons, and make grid a single entity. Lights PID need to be mesh with the mesh length of 2 mm. And we have set min & max length of 1 to 3 mm. Some other quality criteria also defined for better mesh generation. Mesh quality was ‘Tria’ as recommended. After performing the mesh generation. We have seen some quality errors like skewness & min length. There are some off elements found after mesh generation.
Re construct (Mesh > Shell Mesh > Re-construct) – To minimize the off elements, we have used Re-construct option for the visible PID. Even after re-construct there were some off elements were present in the mesh. To remove remaining off elements.
Move (Mesh > Grid > Move) – To remove remaining off elements, there were different ways to do this. Like Cut option, we can check the area of off elements and remove all the unnecessary cuts to remove off elements & and move option is equal helpful to remove off element. Select the hot point of the off element and try to move it till it is showing off elements meshed, then set the hot point.
Body PID - For Rimes & Tires PID, we have removed all the single coons, and make grid a single entity. Lights PID need to be mesh with the mesh length of 3 mm. And we have set min & max length of 1 to 5 mm. Some other quality criteria also defined for better mesh generation. Mesh quality was ‘Tria’ as recommended. After performing the mesh generation. We have seen some quality errors like skewness & min length. There are some off elements found after mesh generation.
Re construct (Mesh > Shell Mesh > Re-construct) – To minimize the off elements, we have used Re-construct option for the visible PID. Even after re-construct there were some off elements were present in the mesh. To remove remaining off elements.
Move (Mesh > Grid > Move) – To remove remaining off elements, there were different ways to do this. Like Cut option, we can check the area of off elements and remove all the unnecessary cuts to remove off elements & and move option is equal helpful to remove off element. Select the hot point of the off element and try to move it till it is showing off elements meshed, then set the hot point.
After doing mesh to the body there are multiple off elements in the whole body. To remove all the sudden off elements, we have changed the quality criteria for all the different PIDs, against the common quality criteria for all the different PIDs, from 0.3 mm to 5 mm. After doing this, all the off elements are now solved. Now we can retrieve the whole car.
Symmetry the Car : To get the whole car, use symmetry option. Transfer > Select entity > Middle click > Symmetry > Mirror 3 point plane > Select three hot point (x1, x2, x3, y1, y2, y3, z1, z2, z3) > Middle Click > Transformation option > Select same PID for other parts too. This is the whole step to get the half deleted car portion.
Wind tunnel creation: Wind tunnel help us to check the running car interaction with the wind. How aerodynamically suitable this car is. Wind tunnels are machines where an object is held stationary inside a tube, and air is blown around it to study the interaction between the object and the moving air. They are used to test the aerodynamic effects of aircraft, rockets, cars, and buildings. Different wind tunnels range in size from less than a foot across, to over 100 feet (30 m), and can have air that moves at speeds from a light breeze to hypersonic velocities.
Wind Tunnel Standards:
For a wind tunnel, there is a fix standard for making a wind tunnel. Wind tunnel should be 4X length from the first point of the car. And for the back side, it should be 6X from the far reach position of the back side of the car. For top surface, it should be 3X distance from the top surface of the body. For side surface, it should be 1X from the car far side point from the both sides.
After creating whole wind tunnels and after selecting all the different PID for each part of the wind tunnel. We have to mesh the wind tunnel. As wind tunnel is too large as compared to the car body. So, that we will mesh the wind tunnel with lesser mesh length near to the car body. And larger mesh length to the area of the wind tunnel which is far away from the car body. For this action, we will use Mesh > Spacing > Factor selection. By this command we can divide the wind tunnel by the equally distributed spacing. And then mesh the wind tunnel in the ascending order from the car body to the far reach point to the car.