# 'TMODELTEST' simulation project by simscale333

#1

I created a new simulation project called 'TMODELTEST':

AAAAAAA

More of my public projects can be found here.

#2

Hi @simscale333!

Can you tell us what you are investigating with that geometry? Is this going to be a CFD analysis?

Best,

Jousef

#3

Yes its going to be CFD ANALYSIS

#4

Great!

Let me know if you need any help from us!

Best,

Jousef

#5

Yes Sir i might require your help, will let you know in this thread. Thankyou

#6

Hey @jousefm How are you ?
Actually sir for this tyre model cfd analysis i wanted results of a case where the tyre is rotating with respect to the ground.
So i am giving boundary conditions as to the tyre as rotating wall velocity and and the bottom wall as moving wall velocity and the top and side walls as slip walls and inlet as velocity inlet for specific spee and outlet as 0 gauge pressure. But the results that i am getting are not coming as expected.
Can you please suggest me what else can be done or whether i am going correct or not ?

#7

Hi @simscale333,

Looking at this project your values do seem nominal. Can you provide more detail on how âoffâ your values are and what you are expecting?

Cheers.

Regards,
Barry

#8

Actually there is very minimal difference in drag force value when compared the same with stationary case of the tyre. Stationary case drag force = 14.40327 N and for rotating 14.34758. So i feel i could be going wrong with the boundary conditions or something else. Can you suggest something please ?

#9

Hi @simscale333,

Can you link me the particular project you are referring to?

Cheers.

Regards,
Barry

#10

https://www.simscale.com/workbench/?pid=5574084291873096663#tab_2-0

Basically i want the cfd analysis for the case that the tyre is rotating at a particular speed on the ground. so how can i achieve that ?

#11

@jousefm @Get_Barried Can anyone of you help me out with the case i want ? i have shared my project in the above message. Thankyou!

#12

Sorry for the delayed reply. Regarding your project you seem to be on the right track, are your results satisfactory?

You might want to take a look at this project, it deals with something more complex than just a wheel but his particular setup should be similar to yours just at the wheel.

Cheers.

Regards,
Barry

#13

Hello @Get_Barried actually sir the main problem is that for the stationary case i am giving my boundary conditions for bottom wall and tyre as no slip.
But in the journal i am referring when they are studying for the tyre rotating case they are applying a moving wall velocity for the botttom ground and tyre as rotational wall velocity.
i gave the same conditions but my coefficient of drag was not found to be of much difference for stationary and rotating case. whereas in the journal i am reffering there is vast difference in the values.
So my main doubt it to create a condition for the tyre rotating with the ground is just giving moving wall velocity to ground and tyre( body ) giving a rotational wall velocity enough ? or should something more should be done ?
i hope i was able to make my point clear.

I will see that project , Thankyou so much @Get_Barried for helping me out so much

#14

@Get_Barried I guess it might be confusing as two which two specific cases i am talking about as ive run multiple cases!

For stationary case - âIncompressibleâ
For rotating case - âROTATING 0â

These two particular cases i am talking about please can you go through them and as you can observe there is not much difference in drag and lift force values whereas the journal which i am referring quite difference is there. So if you can suggest where exactly i am going wrong it will be really helpful for me

Thankyou so much @Get_Barried

#15

Hi @simscale333,

Your setup seems correct for a rotating wheel. Do note I was checking your wheel mesh âMESH HD PARA more cellsâ is much too fine at 59 million cells, you will not see significant value changes and will spend a lot of core hours unnecessarily. Your âMESH HD PARA 1â is sufficient for your uses.

Regarding your mesh as well (I will be referring to âMESH HD PARA 1â), you need to have a rectangular Cartesian box (its currently a cylinder) that extends outwards further in front and slightly behind as well as extending to the sides plus additional height on your wheel. Another mesh recommendation would be for you to perform a simple surface refinement that will allow you to give the wheel âdefinitionâ. You can also do this under âmesh refinementsâ.

Another thing you need to do is a âbounding box layer additionâ to have better quality meshes for the ground effect and a boundary layer inflation where your y+ is less than 1. You can use a ây+ calculatorâ online to determine the values you need and from there calculate out the minimum layer size of your boundary layer inflation.

If you refer to the reference project you will see all these mesh refinements done.

Hope this helps.

Cheers.

Regards,
Barry

#16

Wow @Get_Barried thatâs quite a detailed analysis for my project. Thankyou so much Sir! Really it means alot, i will make the necessary changes as you suggested and will try to run the mesh again. I will get back to you after making all these refinement changes. Thanks alot once again

#17

Hey @Get_Barried i am referring to this project TMODEL
As you told above the mesh refinements i tried to gave according t my knowledge but error messages came thrice with different conditions that the machine ran out of memory.

Can you please give mesh parameters according to your knowledge for capturing air flow around the spokes and name that mesh as " Mesh Barried " ? It will be really helpful for me.

According to the journal which i am referring the only two conditions for mesh is that

1. Minimum edge sizeof fluid around the spokes and tyre region is 0.1 mm
2. Grid size on rest of the fluid region was linerly relaxed by a growth factor of 1.2 when moved away from the tyre.

Can you please run a mesh and show me how to go ahead with it ? Thankyou so much in advance!

#18

The sample project should have been sufficient in showing what refinements are needed, just have to tailor them to your case. Regardless, Iâve meshed the wheel out for you here it should serve as a rough guideline here as youâve requested. The only two things left to conform to are the boundary layer inflation values for a y+ of less than 1 and the exact location to calculate your moments on the wheel.

Hope this helps.

Cheers.

Regards,
Barry

#19

Thankyou so much @Get_Barried for spending time on it and meshing it.
I used an online calculator and found out value of y + as 0.000025 m however just fro my knowledge i would like to ask why did you suggest a y+ of less than 1 ?
Also regarding the calculation of moments on the wheel i have to calculate the drag and lift force for the overall tyre.
Also i wanted to ask for the external aerodynamic cases what value of turbulent intensity are we supposed to consider ?

#20

Ensuring a y+ of less than one would allow you to use the k-omega SST turbulence model at full resolution for increased accuracy. You may use a y+ of around 30 to 200 if youâre using a wall function which will decrease your number of nodes but as mentioned this step is to ensure accuracy since for your case accuracy is important.

That you will have to check the relevant literature regarding your simulation that will define what equations to use to calculate out not only K but also Omega.

Cheers.

Regards,
Barry