Week 4 Challenge : CFD Meshing for BMW car

AIM : To perform a Meshing for a BMW car model and to check the Quality element criteria for a car model.

PROCEDURE :

• In a given model there are many small volumes developed, need to be reduce overall volumes into 5 volumes - 1 is car body volume ant rest four is Tyres volumes.

• First need to topo clean up.
• To to cons solution use length option in Mesh group and give 1mm in both perimeters and Macros.
• Since both half sides are symmetry, only one half side can be correct and do symmetry other side.

1. LIGHTS

1. delete the inner side surface and all sigle and tripple Cons.
2. In outer side of head light single cons present clean it by using paste option.

2. GRILL

1. Remove the excess of surafces, delete the unwanted surface in grill region.
2. Since old surfaces are not in proper use a cut option delete the surfaces and create a new surfaces ny new option in face group..

1. In one of the box need to do 2 boxes but measure is not clear a hot points using a parameter option, first fill first box then second box.
2. Fill all the boxes equally.

1. 

3.LOGO

1. Isolate the logo part, Then delete all inside surfaces properely and use new option to fill it.
2. Remove all the tripple cons, delete the surface which is below logo of car surface .
3. Use extend option below select face and topo it finally select yhe surface which is to be delete below logo and delete it.

4. WINDOWS

1. Remove the tripple cons in windows, sides and above tyres.
2. To fill the single con from outside select project option and select a face, then do cut in top surface use project cut or cut option.
3. Extend the line in ouyer surfaces, then delete the unwanted surfaces, Make a cut on yhe ribs then delete the upper part, Since the parts in side wise is not proper.
4. To fill the gap, can't use direct option by using multiple project select the nodes.
5. Side part - since the surfaces are intersected but it is not showing any layer use intersection tool.
6. Select 1st and 2nd surfaces delete the other surfaces, use cut option and delete the excess surfaces.

5.OPTICAL REAR MIRROR

1. Delete the tripple cons part which is in mirror.
2. The mirror connection rod is connected delete the surfacfe.
3. Make a new surface fully intersection option and delete the surface which is overlapped to connecting of Mirror.

6.RIMS AND TYRES

1. First clear all tripple cons.
2. Select each tyre make isolate yhen clear all tripple and single cons.
3. Remove all the unwanted surfaces below the tyres, to delete tyre surroundings use cons2curve in curves group.
4. Cons2curve used when whole surface is deleted then it will show a boundary line which surface is deleted.
5. Since the bottom surface of the car is not proper, creat a points in the cons2curve by using create option in curves then delete the all surfaces.
6. Create all the new surfaces using by refering cons2curve in a neat manner then delete the cons2curve in curve use delete oiption.

7.ASSIGNING PID'S

1. Assign PIS's for logo, silencer, lights, grills, optical rear mirrorr, windows, rims and tyres and body.
2. use open foam in decks by click the box edit criteria visibility select the unrequired criteria and remove it from the list.
3. select mesh parameter save the quality criteria, in some regions the length of the surfaces are less then target length so to avoid fail, make cut in regions and remove line by rtight click of cut option.
4. The target length of PID'S are

• Grills = 1mm
• Logo = 1mm
• Rims and Tyre = 2mm
• Optical rear mirror = 2mm
• Silencer = 3mm
• Body = 3mm
• Lights = 4mm

MESHING:

1. For Logo Isolate logo check quality criteria
2. For logo minimum length 0.4mm and maximum is 2mm.
3. Give the values in both quality criteria andf in mesh parameter, give perimeter and macros in perimeter group and select a spot mesh option in mesh generations.
4. Then select hidden mode and PID region to see the how mesh are done, to clear the OFF elements.
5. For Grills same procedure as loge but minimum and maximum lengths are o.3 and 2mm.
6. For window target length is 2mm, minimum and maximum are 1 and 3mm
7. For Lights target is 4mm minimum and maximum is 3 and 5 mm, since lights have OFF elements use different kinds of tools to clear it like Move, Split smooth and Cut options based on condition.
8. For Rims and Tyres target length is 2mm minimum and maximum are 1 and 3, in tyre rims many lesser than elements are there so identify and remove the cut the unwanted lines and clear OFF elements.
9. For Siloencer target length is 3mm, minimum and maximum are 1 and 5.
10. For body give target lengthy as 3mm and minimum and maximum are 1 and 5mm.
11. But don't give target length length in length perimeterit can take range between values of the other PIS's
12. after meshing.
13. Click on the OFF element, click on Improve and clear all OFF element.

SYMMETRY

1. Make top view of the model select tranform option click on copy option thyen entities select whole model, deselect the logo part then middle click on symmetry.
2. Click on mirror 3 points plane in use group, select 3 points in the model then middle click check preview themn Finally finish.
3. In some region single cons are presented so by using paste option clear cons error, select paste option in coons group in topo mode, mesh the again.

WIND TUNNEL: Wind tunnel is medium where car is placed and blow a wind, so that nature of flow in car can be determine and do CFD analysis.

1. To make wind tunnel first need to make a path.
2. So that take a total car body length from front and rear side, so consider 'X' term
3. X value is 1300mm.
4. The front face of wind tunnel should be 4X distance so make reference point below the car surface use relative option in points group, and give length as dy as -75.
5. The front side surface l;engthy is from refence point to starting of car ie 650mm.
6. Click relative option and give values in dz as 4*1300+650=5850 to front side.
7. Same as rear siode from reference point to rear of car the length is 610mm.
8. For rear side click dz as -1 and 6*1300+610=8410mm.
9. Similarly Top side So don't take ols reference point .
10. Create new point in upper surface of car so use relative option in upper surface as 3*1300=3900.
11. The sides surface should be length is Xmm, from centre point of front side to both right and left sides.
12. It has to be dx as +1 and -1 and value is 1300mm.
13. crate curve using points.
14. Create 5 new PID'S name as Top surface tunnel, Bottom surface tunnel, Front side tunnel, Rear side tunnel and Sides surface tunnel.
15. Once Bitton surface is crerated top surface to be create by offset option.
16. The distance is 375 to top tunnel height is 3X + 375 = 4275mm.
17. After surface created delete curves of points in bottom surface.

• Finally close all the sides using new option.
• The area of interest in bottom surface is 20mm and Top surface is 100 to this side surface of front and rear side will varies so use spacing option in perimeter group and change Linear to Geometric, Facto of safety is 1.1, dmin is 20 and dmax is 100.
• Click on con in bottom side so that arrow in upper direction facing, there is no need to give values in meshing quality because length of cons values is varies. \

LEARNING OUTCOMES :

• In this week I learnt different new concepts.
• How a whole car have been meshed in step by step.
• The differnt concepts of procedures learnt and it is to length process.

RESULT :

The surface model of the car meshed in given target length and different kinds of error are determined and cleared, The result is calculated and both car and winf tunnel is meshed and OFF elements of the whole model is Zero.

The image is attached below.

CONCLUSION:

• The whole car model details of knowledge is learnt step by step.
• The Problem solving and identifying the errors are noted.
• Different type of problrm in different procedure had identified, thge process takes time but during this task I have learnt new skills, I enjoyed the process, process of meshing solving the errors and finishing the task.
• Overall the meshing of both car model and wind tunnel surface is prepared.

The model is uploaded in Google drive, link is : https://drive.google.com/drive/folders/1SpDoUysVtB_NOcvjVtgzdJQeDX9PxQqN?usp=sharing

THANK YOU