Import pressure using linear interpolation

Hello everyone, I'm doing a analysis to find the displacement and stress on a wing under the pressure field. And I imported the pressure field using linear interpolation with the data export from Ansys. And I have encountered a problem, the pressure field supposed to act in the outer surface of the wing skin. But instead only a part of the pressure is acting in the outer surface,other part acting in the inner surface of the wing. Could anyone tell me, why is that happening? And how can I correct it?

I would be very grateful to receive your answers. Please help me out!

Thank you so much!

P/s: I have uploaded here, the picture of my problem, the .hm file, and the pressure file, if you need to see it.

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tinh

Hi,

I am not sure what reason is. But to fix it, you can enter panel tools>normal, reverse normal of elems with 'red' color outward

then enter analysis>pressure>update . select all pressure, set direction as 'normal' then click update > vector > update

Altair Forum User

Hi,

I am not sure what reason is. But to fix it, you can enter panel tools>normal, reverse normal of elems with 'red' color outward

then enter analysis>pressure>update . select all pressure, set direction as 'normal' then click update > vector > update

Hi, thank you for your help. I've done what you told me. But In the update radio button, there is no option for linear interpolation. So after a reverse normal of element with red color outward, I recreated the pressure. And the result is opposite. And not all the pressure is acting on the outer surface as you can see in the picture below. What else can I do to fix it? Please!

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QuyNguyenDai

Normal vector is the same for the mesh. So if you got different pressure by doing mapping, the only cause is in your CSV file.

However, it seems to me logic. You have always different pressure between faces. By this way we got the lift, right?

Anyway, check you CFD pressure again.

Altair Forum User

Normal vector is the same for the mesh. So if you got different pressure by doing mapping, the only cause is in your CSV file.

However, it seems to me logic. You have always different pressure between faces. By this way we got the lift, right?

Anyway, check you CFD pressure again.

Thank you so much for your answers!

Yes the different pressure between upper face and lower face make lift, but the problem I got here is that the pressure is not all acting on the outer surface. I have rechecked the CFD pressure again as you told me (even though I've check it multiple times before). This problem is so weird, I used the pressure file to import into other model, and it's find, all the pressure is acting on the outer surface. Don't know why it's different for this model.

tinh

Hi, thank you for your help. I've done what you told me. But In the update radio button, there is no option for linear interpolation. So after a reverse normal of element with red color outward, I recreated the pressure. And the result is opposite. And not all the pressure is acting on the outer surface as you can see in the picture below. What else can I do to fix it? Please!

<?xml version="1.0" encoding="UTF-8"?>

In update panel, you need not to provide linear interpolation, we just update 'vector' . Do step by step as I guide first

Altair Forum User

In update panel, you need not to provide linear interpolation, we just update 'vector' . Do step by step as I guide first

Hi I did as you told, I choose the pressure in loads and only update the vector. I got the pressure field all are acting on the outer surface. But then I noticed that the magnitude for the pressure seems to be multiplied to 10^4 times, not the original one. I also send the picture illustrated what I done in the update. Could you tell me, what I've done wrong please?

Thank you so much!

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tinh

Hi,

I am not sure. maybe => altair's bug /emoticons/default_biggrin.png' srcset='/emoticons/biggrin@2x.png 2x' title=':D' width='20' />

anyway, I found that in your csv file, pressure values are in different sign (sometimes plus, sometimes minus)

so it generates reversed pressure vector

Open it by excel and use abs function to unify pressure values. Then import it again => ok

sample:

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Altair Forum User

Hi,

I am not sure. maybe => altair's bug /emoticons/default_biggrin.png' srcset='/emoticons/biggrin@2x.png 2x' title=':D' width='20' />

anyway, I found that in your csv file, pressure values are in different sign (sometimes plus, sometimes minus)

so it generates reversed pressure vector

Open it by excel and use abs function to unify pressure values. Then import it again => ok

sample:

Oh, so it's because of the negative pressure value which caused the reversed vector. I got it. Thank you so much to help me out. I'm very grateful!

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tinh

Suddently thinking that, if pressure values are all minus or all plus then how the wing can fly?

Do you still think pressure vectors need to be unified?

QuyNguyenDai

Suddently thinking that, if pressure values are all minus or all plus then how the wing can fly?

That why I asked him to check input (CFD pressure) /emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20' />

Altair Forum User

Suddently thinking that, if pressure values are all minus or all plus then how the wing can fly?

Do you still think pressure vectors need to be unified?

No, I don't think the vector need to be unified anymore. I think the first picture I posted in the question is correct. It's not wrong. First I thought that the pressure value I import to HyperMesh will maintain its value(include the sign) so that, the vector should be unified. But then when recheck the imported pressure value. It's all positive, so the vector of the negative one must be at the opposite direction.

Arthur Rocha_21027

Hello, i have some question about your model, does the original system of Hypermesh and the system of the software you used to get the Pressures be the same? I mean, the (x,y,z=0,0,0) of hypermesh have to be the same of the the other software. I am trying to run the same analysis with a differente component and pressures, but i can't apply the pressures in a correct way.

I don't know if i was clear about my problem, but if anyone could help me i would be very gratefull.

Arthur Rocha_21027

Hello, i've tried to import a .CSV pressure file to hypermesh, but the pressure distribuiton is not the same as the CFD analysis, the system reference is the same in hypermesh and CFD analysis. If anyone can help me i would be very gratefull

Thanks in advance

AMV

How you created the pressure file from fluent and how you imported on Hypermesh?

thanks in advance!