Week 4 Challenge : CFD Meshing for BMW car

AIM : For the given BMW M6 model car resolve all the geometrical errors on the half portion, assign PID's, perform mesh using the given taget lengths and quality
criterias. after performing the mesh on the half portion do syetry on the other side

target lengths

1. Body : 3 mm
2. Grills : 1 mm
3. Lights : 4 mm
4. Rims and tyres : 2 mm
5. optical rear view mirror : 2 mm
6. window : 2 mm
7. Silencer : 3 mm
8. Logo : 1 mm

PROCEDURE

1. download and import the model onto the ansa tool, using shadow view command turn the view into 3D from wireframe model

2. using the checks manager> geometric checks check for the geometrical errors, through which the error in the models, coons and penetration to the surfaces can be located

3. To resolve the geometrical models, concentrate on a single part at a time and isolate the part from the rest of the body using NOT command/ option , then lock option
is used to lock the selected entity while perforing clean up
the selected part is checked for errros and resolved

GEOMETRY CLEAN UP

starting with

. FRONT GRILL

the errors can be seen, presence of triple cons, intersection and penetrations as well as improper geometrical fitment

cleanup of the surfaces that are unwanted and which are on the inside, aswell as the deleting and filling up of the surfaces to create a water tight model
at some places there had to be coons to be cut inorder to isolate the particular surface to delete

. The front ribs on the grill had no contact to the surface on the main body of grill so the coons had to modified by deleting the excess and unwanted surface, then projecting the coons
of the ribs to the surface and the finishing it up by clearing of the edges and recreating a surface, thus making it attached to the surface and making a unibody

. The rest of the grill upper and fog lamp garnish are resolved using the same methodology as the above said for the lower grill member

. Deleting the excess surface causing the triple cone error and deleting the rear surface

. closing the surface b/w each of the grill part as the rear surface was deleted which left a opening,

. Excess of the rib are chopped off by cutting the cons and thus marking and seperating the surface to the deleted as previously the upper part had no contact to the grill
surface , after which the surface was recreated

. foglamp cover part

. Same as the upper part deleting of the many surfaces that had led to triple cons had to be deleted

. The surfaces and coons had to trimed in order to create a non interfering and smooth closeup geometry using cutting the coons and as well as deleting some areas and
recreating completely new surface

. REAR VIEW MIRROR

. Deleting the excess overlapping surface to avoid intersection and triple con errors

. Deleting the internal entities and the surfaces on the outside to resolve single coon errors
the deleted surface voids are recreated using new face command

. TYRES

. intersection of the surface, resolved by deleteing the excess and unanted surface, any voids while deleting are recreated

. LOGO

. Presence of triple coons can be treated by deleting the unwanted internal surfaces

. After the triple coons are resolved by the deleting of the phases there are some surface voids which are then recreated by developing the new surface using new faces feature
some single coon errors can be resolved using topo or by projecting the coons to the neighbour inter releated surface, the errors which then are not resolved using those
techniques require deleting of the entire surface and recreating them again

. the surface in the middle had a small rise to the next surface making it to appear non-uniform to resolve it the entire surface was deleted and recerated

. The monogram design of the BMW logo has some issues as the letter M and W have some flat planer surface , that can cause some issue as the node size will be less than
1mm as the target length for the part required to be meshed is 1mm, which are resolved by deleting the small flat surface and recreating it to a sharp edge

. SILENCER

. The inetersection / penetration of the surfaces can be resolved by deleting the internal part of the silencer which isn't needed as its existance can cause to develop its own volume
while performing mesh. To avoid it the internal part can be deleted by releasing the coons which have the connectivity to the internal and the outer part using release coons options
thus isolating the internal and the outer part of the silencer and the internal part can be selected using PID region option and deleted

. BODY

. Many of the triple coons in the body can be easily resolved by simply deleting the overlapping the surface

.This particular spot has triple coons as well as single coons to resolve them overlaping surfaces are to deleted and some surfaces where in the single coons are presented are
required to be completely deleted as topo or projecting coons wont work, the rear surface where a duct like surface is present is also deleted as well as the openings are to be closed
by creating whole new surface to make it water tight

. The intersecting surface of the wheel wells can be deleted and the tagged surfaces along with the wheel wells that get deleted are to be recreated , so that the surface appearance and the integrity can be maintained healthier while the time of meshing as the sharp and concave edges and coons can be resolved in the process
and before deleting the surface to acess the history and location of the existing surface the edges are marked up using coones2curves command which comes in handy while recreating

. once the half of the car is resolved from all the geometrical errors then the other half is recreated using the transform tool

. PID's

. Performing surface Mesh

. clubbing the items to be meshed in the same length
grills and logo's as target length of 1mm

. After the meshing there would be soe errors such as off and unmeshed elements which can be resolved using improve option where it tries to fix the errors itself by
reconstruct/reshape/smooth/fix quality operations and resolve the errors, if so it is not fixed the next option is to delete the geometrical surface and create it again using
different algorithum and combination

. Tyres, rear view mirror and windows , target length 2 mm

. Lights , target length : 4mm

. Body and Silencer , target length : 3mm

construction and surface mmeshing of wind tunnel

. for constructing the wind tunnel the parameters are that the perimeter boundaries should within 4x distance to the front of the car as well as x distance to the sides, 3x from the
top, the bottom face of the tunnel should be at a minimal distance as not to be in contact with the wheels of the car, as X denotes the overhaul length of the car

. using the relative option in the points menu the midpoint node in the car taken as a reference and specifying the distance and position, respective of the perimeteral boundary points
position, after which the points are connected using curves. this curves are then used to create a plane/face using new face option.

. The newly created plane forms as a reference now which helps in the top plane creation, parallely lying plane is taken as a to make offset reference.
from then the side planes are created with the top and bottom plane edges.
after the planes are created assign respective PID's as top, bottom, front, rear and side faces of tunnel

. as the wind tunnel is required to be meshed with a mesh of growing nature from bottom to its top within a range of 20mm to 100mm
to accommplish it the upper and lower faces of the tunnel are individually meshed with the recommened values, after which the side faces are meshed in which the spacing factor is
specified from the start limit of 20mm to end limit of 100mm

link to download the model from the drive : https://drive.google.com/file/d/1th8RtuZWl13UQkA2AIR9xKqIn7ENCz-n/view?usp=sharing