Week 4 Challenge : CFD Meshing for BMW car

AIM:TO PERFORM CFD MESHING FOR A BMW CAR AND CREATING A OUTER ENCLOSURE ANG
GENERATING VOLUMETRIC MESH TO PERFORM OPEN SIMULATIONS USING ANSA

PROCEDURE:

Firstly i have imported the model of BMW car into the ANSA software. Generally it opens in the Topo deck where the geometrical cleanups have to be done and after observing the model i found that the model is symmetrical about central plane and then using delete option available in the faces bar i have deleted half the model because after perform CFD mesh on the half model using symmetry option available in the transforms section i will replicate the model to the other side. to begin with the cleanups i have selected the individual parts, firstly i have taken the lights to perform cleanups by using inot option and deleted the the internal layers because we are concerned about external simulations using the delete option available in faces section by selecting the face to deleted and middle mouse click to delete . Then went to checks manager and then geometry checks and found is there any triple con or single cons and also intersections and penetration issues. After clearing the all the issues i selected mirror as it is a small part i directly went for geometry checks and found there are penetration issues solved by using the project option by selecrting the cons which are meant to be projected and middle mouse then selected the face upon which the cons are to be projected then middle mouse and then using the delete option i delected the face which is at the interface of two and there double cons are formed from triple cons . Then after i have chosen grills for cleanups here i have used the extend option to extend a face in a particular surface direction by clicking on the extend option and selecting the face which have single con and then the surface direction on which side it has to be extended and then after i chosen tyres to perform cleanups there i created faces by deleting the previous as their orientation was not appropriate .then have chosen silencers and then windows and then the body for cleanups . while performing cleanups for the body mostly used options were extend option ,intersect, faces new and planar option. Then after finally performed cleanups for logo and then selected on all to view the cleaned up half BMW model and went for geometry checks and found single cons which are actually at the part we have deleted and then went to PID manager to assign pids and the PID i have assigned are Body, Lights, Grills, Rims and Tires, Optical Rear view mirror, windows, silencer and logo by going to the pid manager and then clicked on new and then shell property as assigned the names and to assign the part i went to the each pid name and then right click and then left click on apply and selecting the part of the model to be assigned and middle click and done . then went to the compress to delete a pid if it has been assigned twice.then i left with 7 pids as i specified above.Thenafter went to the mesh deck to perform CFD mesh and performed CFD mesh by choosing the min and max length differently for each PID which are as follows

1. Body - minimum length 3 mm and maximum length as 4mm
2. Lights - minimum length 4 mm and maximum length as 5mm
3. Grills - minimum length 1 mm and maximum length as 3mm
4. Rims and Tyres - minimum length 2 mm and maximum length as 3mm
5. Optical Rear view mirror - minimum length 2 mm and maximum length as 3mm
6. Window - minimum length 2 mm and maximum length as 3mm
7. Silencer - minimum length 3 mm and maximum length as 4mm
8. Logo - minimum length 1 mm and maximum length as 2mm

and to perform cfd mesh firstly i have selected the which have same minimum lengths and then went to the mesh parameters tab and given the minimum and maximum lengths as above and then ok.then after i came to perimeters deck and then selected spacing and perimeters and middle mouse and done .then after went to the mesh and cfd and the visible to dispaly the mesh. similarly i have done for the remaining pids as well.after meshing all the pids performed quality checks by enabling min and maximum lengths in quality criteria and also skewness given 0.7 .to perform quality check a relaxation of 1mm given on both minimum and maximum lengths and all these values were given in the quality criteria section and then ok and view the off elements we have to go the hidden option available in the bottom bar and on the bottom left we can see the no off elements they are the ones which didnt obeyed the one of the three criterias and overcome the off elements we have to go to the reconstruct option available in the shellmesh and then select the model and done .if it works for few elements and inorder to overcome remaining we got smoothness option available in the shell mesh itself .if there are off elements still we manually make it to go by moving the grid points by using the move option available in the grids section . finally made the meshed the model in such a way that no off elements were present and after performing the CFD mesh using the the transform option and copy replicated the mesh model to the other side so that completely meshed BMW car was formed generate an enclosure firstly we need find the pivot point that is the base point ,Using the measure between the nodes and aslo between the cons we found the length of the car in all the directions .firstly a point is projected on the extreme corner of car and using that point as trelative point i have generated one more point at particular distance that is 4times the length of the car by going to the points relative and a new tab appears where we need specify the distance and done and using the generated point i creates a relative point to the bottom of the car and deleted those points previous ones and using the point i generated more points relatively on both sides and using the three points i created more three points relatively on rear part of the car then create curves i joined all the points and created a face and using offset and specifying the distance i generated the same on the top and in using the create face option and planar faces have been generated, we have generated an enclosure .surface mesh has be been generated using spot mesh command and then went to volume deck to to generate volumetric mesh inside the enclosure and outside the model for open simulations and went to define volumes and delete the unnecessary volumes and left with volume inside the enclosure and generated. A snapshot of CFD meshed model for open simulations attached.

RESULTS:

https://drive.google.com/file/d/1TrTjxj4FV1cHLqkcGuvjkCBzE45Fpsja/view?usp=sharing.

CFD MESHING FOR A BMW CAR AND CREATING A OUTER ENCLOSURE AND GENERATING VOLUMETRIC MESH TO PERFORM OPEN SIMULATIONS USING ANSA