Two dimensional meshing of BMW-M6 using ANSA

Objective-

To remove all topological error for surface meshing of all parts of car .After removing all errors in meshing wind tunnel should be prepare for computational fluid dynamics application.for two diamensional surface meshing following contrains should be use

• body- 3 units
• light- 4units
• grills-1unit
• tires and rims-2units
• window and mirror- 2 units
• silencer-3 units
• logo-1 units

for wind tunnels size should be like following

• wind tunnel.s stracture having six side like cube
• consider x= length of car
• front length of tunnel from front point from car- 4*x
• rear length of tunnel from rear point from car- 6*x
• top length of tunnel from top point from car- 3*x
• bottom is road

sideward length from symmetric plane of car- 1*x

1.1 steps to remove topological errors

• use geometry checks to find any coons .
• pid and entity should on from drawing toolbar
• to remove that single coons use of following steps

1.1.1 deleting extra contor line which are due to cad engineer

• select macos from faces drow toolbar and delete that using universal delete option below image shows that extra contor line

1.2 to visualize the geometry better

use mesh (from module toolbar)- meshing - length perimeter size as 1 units now observe the following image better curve visualization is done perfactely

1.3- removing first single cons below image shows its location

use !NOT option - pid region to select body-

• Approch

1. first isolate its from other surface and then fill up that face
3. now toppo (module)- faces section (module bttons)-select cut -select desired cut poind and middle click of mouse to confirmed it below image is result
5. after that use delete option from faces section and delet taht entity entity is shown below
7. after deleting that enity create new entity by -faces section - new coons their- below image is after creating of coons surafce

1.3 removing another single coon-

Below image shows location of that cons which is selected to remove cons

here its observe that some part of that cons surface is missing or hiding due to use previous

!NOT option to bring back that geometry use ALL to show hidden geomertry .

now use ! not option and pid region to select that part from other side also

above image show after click of middle mouse button (that is confirming that !NOT -pid region option) use middle mouse button again an then see below image to confirm sucessful landing of that hidden part ehich actually part of original car body .

1. to better visualize that part (use lock button first ) use NOT button _ entity - to hide unnecessary part
3. now removing that first conns by choosing below surface
5. use project option from faces section of module button toolbox
7. select single con first confirmed it with middle mouse button then select desired surface to project that. below image is showing hady caption of that desired surafce (note that from option window paste,split original,connect with face should be checked like image shown in 6 step.)
9. repeat same procedure from 5-7 to remove that cons to solve that below con which shown or highlighted in pink colour also
11. now another option can be use as same project which is in module button section faces and that button name as- extended use that to solve below pink highlighted single cons.
13. select extend- select single cons- middle mouse button- use desired surface to project on
14. due to this small singe cons is generated like below image
16. to remove it use project button and same procedure (5-7 steps

1.3.1 now addressing to solve toplogical errors inside that geometry (below image shown that) and later on its should be delete to facilate that surface deleting following are some steps--

• this surface shoud be intersect with body geometry

1. use intersect option to intersect that two surfaces which are shown in below image
2. after merging that triple cons are generated like below images
4. that triple cons which are shown in above images should be deleted to cleanup that topological errors
5. to delete that use universal delet option below image shows final result
7. now box shown in below image should be delet because its extra and not needed in cfd analysis (close surfaces are only need which are single volume)
9. use universal delete option to delete that and below image is result
11. then encountering another cons which are highlighted by black rectangle in below image
13. to remove those cons first generate surface there like below image by - fitted option in face section by selecting new button in module buttons
15. after crating that surface another single cons is automatically generated and that should be intersect with write surface to get rid of that single con below picture show visualization of that sufaces.
17. after that select faces section -delete option to delete that extra surface below image shows aftereffect of that deleted surfaces
19. below image show undesired surface which should be deleted
21. after deleting that nice clean image which is like (below image ) ,show that deleted surface to better visualization.
23. below GIF image shows another single cons to get rid of that use following steps
25. use project option from face section -(module button)-to solve that single cons after solving its should look like beolw image
27. by deleting extra surafces below image shows cleare and clean image .Or desired final image and its should be same geometry from other side alse and that is taken care with symmetry option .
29. now solving and patching another single coons which shown below

1.4-single coons and triple coons (three surface sharing single edges) fixing (to generate perfect volumetric mesh)

• above image shows triple cons which is to be fix - use module buttons - coons section - release button(isolate to surface after left clicking on any cons --ex- triple or double conns converted to single cons)
• after that paste option from - cons section select it and middle click now its converted to double cons like below image

1.4.1-single coons and triple coons (three surface sharing single edges) fixing (to generate perfect volumetric mesh)

• Removing volumetric triple cons at all windows follow below process .By doing this process that voumetric window is converted to double cons and its only required in volumetric meshing .
• first use !not - pid- option to bring back that window below image show clear visualization on what is that triple cons is in process to remove
• after that deleting that volumetric window now all windows should be like below image

1.4.2 now clearing toppo errors at BMW logo (removing all triple cons)

-select !not - entity - then use project option like below image

-after that delete(face section) that extra surface which are at backside of logo

-above image shows aftermaths of deleting option

-bring back whole geometry -by selecting All in order to delete that surface incosistency which shown below (surafce splashes that means too surace are intruding one another)

-select !not on that batch and again project that on front panel

after use of project see backside of front panel and perform delete option to clear that toppo errors

-delete that logo of BMW because its not creat verry small drag and fill that hole below image aftermaths of above all operation

-hence geometry clean up at logo is completed-

1.4.1 removing topological errors at grills (image shown below ) to have the volumetric mesh their ,that grills must be hollow so mould like cavity must form to ease of volumetric meshing (interier and exterier should be one entire voume and that only fit for CFD analysis)

• its clearely seen above image thaere are to surfaces intruding one other (surface splashes)(two surafce ovelap each other) to remove this type of error perform following steps
• use delete option from face section of modules buttons
• after deleting that splashesh surface now image is clearly shown below
• now deleting also that extra surface which shown and select in above image
• to make that grills hollow its must separte first by deleting that faces which are shown in below image
• after deleting that use cut option to always cut that extra surface(with in option list parametric cut ,heal cut and delete hot points should be ticked on )
• after that like above image fill up that cons likw above image
• do like below image always and repeat this process untill and unless all that grill are clean up and fill that coons like below image
• now above grills are good for CFD analysis and to generate external volumetric mesh due to all that fins of grill cover .
• this above front geometry also at other side also to clean that toppo errors on that geometry also one can be repeat all above process or by mirroring that on other side is good and better option also available in ansa first bring those parts which to be mirror like below image
• first delete that other( symmetryical side grill) and then use transform option from utility toolbar - select copy by holding transform - after that drag and drop all over that geometry like below image

• then middle mouse click another window will appear -select symmetry -use three point symmetry like below image
• select any three point which are must define symmetry but not they should not in same line and they should be on same symmetric line but in different plane.
• after making that mirroring use past option from cons section of module buttons ,To fit that mirrored image in new shell below GIF must correct visualization of that so that single cons which are near to newly crated entity by mirroring of image must vanished or get converted into the double cons like below image

1.5 working on car like symmetric approcch

1. first hide tires and rims (usinf NOT- and pid ) because they may be or may not be symmetric
2. use F1 key -use delete option to delete half geometry
4. Here key point is at symmetric edge only single cons should be allow by Ansa so that softwaer can perform or generate symmetric geommetry on other side
6. above image shows triple cons at that symmetric edges and its should be deleted first , then delete that volume like surface also which shown in below geommetry so that external volummetric mesh generate very well (only closed cavities are allowed) by deleting that surface image now looks like below .
8. now first delet that face like below image and then use project option (because while deleting its select unwanted surafce also ( so lat\'s isolate with that project option and then delete that face))with (paste,connect with faces ,splite original curve in green ticked mode )
10. now to making cavity in that grills use paste option for paste that single cons or attached any two surafces , release option is used to deatached any two surface ,cut to generate any missing surface
13. above image shows entity whichs flickering to get rid of it first delete that face - use project option and then after that again delete that unwanted surafces
14. HERE making cavity like shown below (first two cavity like grill are output of above [project,paste,release ,cut ]steps)
16. now perform following steps to creat cavity in that pink region which is highlighted in below image
18. first project that like below image (choose edges then middle mouse click to project on that respective face so that its get isolate and ease to delete that face)
20. then delete that extra suraface - first use cut to join two unconnected surfaces then perform universal delete option - by using module buttons - face section - new - select cons to generate new better surface -below image shows aftermaths of solving that grills
22. see above image now that grills are clean and hollow like cavity (and side image which is red highlighted shows at symmetry plane single cons are present and that is only desireable and { show sucessuful conversion of that teiple cons to double cons}

1.6.1 fixing head light (inner volumetric geometry should be deleted to reduce volumetric mesh computation)

1. first use not option to hide that external surafce then use lock option -then delet all inner geometry
2. after that use all option to bring that external surface back now fill that single cons which is present their now geometry should look ike below

1.6.2 removing topological erros in front sided grill which shown below(making grill like cavity )

1. use universal delete option to get rid of that surfaces splashes (due to intersecting two surfaces )
2. now here also grills are converted to cavity and then its get cover up
3. below image shows after effect of deleting all that unecessary surfaces
5. now making cavity on that grill - use universal delete option to delete that surfaces which are shown infigure and cavity in grill be crated
7. after deleting that use project option by selecting (below image)pink highlighted edges on that perpendicular grill
9. now use intersect (from hot points section to generate hot point {edges option should be green checked} )
10. after deleting that use mesh (module)- select any point near that surface and delete that unwanted surface like below image
12. now use new- (toppo module)- fitted to generate that suraces like below images shows aftereffect

1.6.3 now covering up that grill which is in 1.6.2

1. use extrude option (module buttons faces section)- grill -to generate extrude surface -then use new-fitted option to generate below like entity which is cover up with double cons

1.7 setting model browser tree(assigning name or making groups of parts like below image)

- select !not-PID- (select any geometry)-(then use middle mouse button visible only that parts) -then go to model browser -take option of set part (drag and drop over desired part then middle mouse button to confirmed it)-then new parts are generated like below image (use parts visible-make part whatever visible on screen,,use group visible - to make group of elements whatever visible on screen )

1.8 removing topological errors on body (light on that body {from model browser[so body only be visible]}

2. above image shows extra surafec it has to deleted
3. first use intersect option select surafces which are shown below image
5. after that delete that unecessary surafce which are red highlighted in 1.8 section step 1 image
7. (above image shows unwanted single cons )then start working on botton side of body delete undesired an intersected surafce and make that bottom surface like below shown image ( use new-to patch up ,cut to delete unwanted surface)
9. above picture shows all single and triple cons deleted and good surfaces is generated

1.9 setting or organizing property

1. use set pid button to select and assign name to it
2. first light up in model browser which is to be set pid ; say lights
3. then goto prperty - hold on serch symbol select visible from drop down menu -then goto set pid -select it middle mouse button to assign that prperty
4. below image shows every parts gets its required pid
6. then use compress entity

1.10 cleaning triple cons at wheels (to make whole volume(For cfd analysis))

1. wheels having rims and tier segregating from each other first by projection option like below
3. then delete that intersecting surface(that are shown in side image in second step) to become one whole volume

1.11 now checks geometry first (before meshing)

1. goto checks - geometry-run-then (eliminate that all cons which are unwanted )
2. before going to surface mesh every toppo errors should be removed

2.1 2D meshing

1. goto mesh(module-set length -primeter )-after assigning the respective mesh size then use -free (mesh section)-hold left clck-select visible
2. body- 3 units
3. light- 4units
4. grills-1unit
5. tires and rims-2units
6. window and mirror- 2 units
7. silencer-3 units
8. logo-1 units
9. presentation;proximity -set to 0.5 (set to absolute value)
10. goto-mesh parameter -general-min length 0.9-max length-5-distortion as 15
11. then remove all mesh errors which are are shown by mesh check manager
12. then for mesh quality (mesh manager) to remove that
13. goto-quality criteria following should be selected as
15. below figure shows all skewness,minimum and max length are corrected
17. mesh(module)-cut -to remove any presentation:interaction (by right clicking)-from option list (remesh macros ,heel cut ,delet hot point should be on for bhoth mouse clicks)
18. skewness is remove by using (module) mesh-cut(section macros),mu-surf({Grids}moving nodes of traingle to remove skewness),
19. min and max length errors are removed using-reconstracting the mesh -{shell mesh section}(recontract minlength 0.2 and max length as 5)

2.2 meshing the wind tunnel and making symmetry

1. use copy-symmetry section -tree point symmetry (select any random {should be in different plne but along symmetry})-and middle mouse button to generate that symmetry like below image

2.3 wind tunnel for CFD analysis

1. to make wind tunnel make tunnel of size by given size
2. wind tunnel.s stracture having six side like cube
3. consider x= length of car
4. front length of tunnel from front point from car- 4*x
5. rear length of tunnel from rear point from car- 6*x
6. top length of tunnel from top point from car- 3*x
7. bottom is road
8. sideward length from symmetric plane of car- 1*x
10. to make wind tunnel first -goto- points section (from toppo module)-set point on car then middle mouse button (window will open select apprpriat direction to set point give length say - in dz=four times of length of car=5400 )
11. then use toppo module-curves section new button -select that two point to generate reference line
12. then goto points section ( to generate plane three points needed)-put appropriate distance to generate points there (dx=100, dy=100)
13. after genearating that extra two points to specify plane now in total three points are there (one from before dz=100)
14. then use plane (surfaces section {module-toppo}) -(select that three points )-to generate plane (use drag and drop to specify any size plane)
16. above image is wire frame model with wind tunnel with 6 unmeshed surface of wind tunnel
17. for two diamensional mesing of wind tunnel use mesh size as following
18. for bottom side of tunnel mesh size as 20 units
19. for top side of tunnel mesh size as 100 units
20. inlet and outlet wall mesh size as 50 units
22. above image shows 6 unmeshed surfaces of wind tunnel .
23. below picture shows refinement of walls are done for bettrt CFD analysis tool used as mesh (module) -( perimeter section)spacind -(geometry from dmin -20-dmax100)

conclusion-

As per requirement all after removing all topological error two diamensional meshing is done.Here volumetric meshing and surface meshing of wind tunnel is not done because its requires a lot of computation time and higher computational processer as well.