Week 4 Challenge : CFD Meshing for BMW car

Objective- CFD meshing for the BMW M-3 Car.

Introduction – CFD meshing over the BMW M3 car while making it a single volume first and then at the end placing in the wind tunnel to see the CFD properties accordingly by the use of ANSA V22.1.3.

Procedure- this is the very lengthy process and performed step by step, here I am going to add all the necessary points and tools which was used to complete the process.

Step-1 topo clean-up

• Overlap surface
• Single cons
• Tripel cons
• Patch over the surface
• Very small surface
• Penetration between surface.
• Also the vehicle was not fine and smooth so to make it smooth use either auxiliary> fine tool or under mesh give the whole vehicle as a 1mm target length for both perimeter and macros.

Step-2 we need to make the whole car in a single volume to performed the CFD analysis, for this over the whole body all the unnecessary inside volume and unwanted surfaces are removed, but this is all the very time consuming so for this we made a cut on our BMW from Middle as the whole car is symmetry about the centre except the logo.

Step 3 assign the PID to all the different part like Silencer, head light, windows, body, mirror and grill.

Step 4 in this part we have to provide the different quality criteria to different PID as according to the target length.

Quality criteria< open form< skewness< min length, max length< mesh parameter< tria< min and max length< target length< perimeter < macro< spot mesh< hidden mode< enable quality criteria< look for the off elements< reconstruct< visible.

To work for the off element we can also use move the node, smooth and origin tool to consider our off elements.

• Body-3mm
• Windows-2mm
• Grill-1mm
• Rimtyre-2mm
• Light-4mm
• Mirror-2mm
• Silencer-3mm
• Logo-1mm

Step-5 bring back the isolated half or deleted half part of the vehicle by using transform< copy< 3 point symmetry< any tree point over the vehicle body< finish< now paste the two separate cons so the whole body can connect to each other.

Step-6 build the wind tunnel around the BMW car by the use of surface but it has some length parameter.

For the front and back it has the 4x distance, where x is the distance from centre to the start point, similarly top has to 3x and left and right has to be the 1-1x distance after that we will use point method to locate the point and then by the use of curve construct we will construct the curve and by the help of this curve will use fitted option to build the whole surrounding near the body.

Step-7 now the final part 3-d mesh define the volume and delete the unnecessary silencer and tyre part , our whole concern was from starting is to make it in a single geometry so we can give this as a single volume.

Result-

 

 

Learning outcomes- in the meshing process of the BMW car in this challenge I came up with the lot of difficulties and challenges while doing all the steps, but at the end the challenge is successful as according to the need.

So here the primary learning was the tool a lot of new tool like fine, smooth, move origin, cons to curve, reconstruct, cons release, paste, compress, cut mirror, copy off set, node and spacing relocation are  used and got the idea of the working of this tool.

Quality criteria under the open form was also the learning, skewness under fluent and the length parameter for the same was performed here for different tool.

Building the wind tunnel for the model with all the surface was my first ever drafting by the use of ANSA software.

Conclusion- ANSA is very vast software I got the idea of the basic tools, but to perform the meshing on different models in the industries with proper design and the given calculation also on very bulky structure is quite a difficult and challenging work.

After this challenge I got the little bit idea about how one bulky project in the industry will look like and which type of possible problem can be faced there and how to overcome them.

 BMW is a milestone in an automotive industries and its cars are equipped with various critical surface geometry and working on this type of geometry as the project gives some confidence.