Learning Forum

[shing97]

[Rob]

You can define regions to patch, or set a fluid region in the geometry & mesh and then patch that. n

[shing97]

Hi Sir, thanks for the reply.nBut if we define the regions and patch, it will be the initial condition where the substrate has been filled with the encapsulant?nThe initial condition will be as shown in the picture that I attached below. Then I want to fill up the region as shown in the second picture below. No matter how I try the results I could get is as shown in the third picture. （the fluid has a density of 1800kg/m3 and viscosity of 448cP）nn

You can define regions to patch, or set a fluid region in the geometry & mesh and then patch that.https://forum.ansys.com/discussion/comment/110879#Comment_110879

n

[Rob]

Yes, that will be the initial condition. nIf you're expecting the sketch as the final result, have you run the model for long enough, and what is there to stop the blue material filling the entire domain? n

[shing97]

Yes, that will be the initial condition. If you're expecting the sketch as the final result, have you run the model for long enough, and what is there to stop the "blue" material filling the entire domain?https://forum.ansys.com/discussion/comment/111020#Comment_111020

I have tried to change the udf condition to make the fluid-filled in the substrate longer (the sketch i want), but the shape I got is shown as below:nThe sides of the fluid are getting higher yet the middle side is lower.nn

[Rob]

Look at the flow field, ie vectors of velocity and wall conditions. From the image I can think of a scenario for either result, you've not given any reason why one solution is correct and the other not. n

[shing97]

Look at the flow field, ie vectors of velocity and wall conditions. From the image I can think of a scenario for either result, you've not given any reason why one solution is correct and the other not.https://forum.ansys.com/discussion/comment/111069#Comment_111069

Okay I will look into it, thanks Sir.n

[shing97]

Look at the flow field, ie vectors of velocity and wall conditions. From the image I can think of a scenario for either result, you've not given any reason why one solution is correct and the other not.https://forum.ansys.com/discussion/comment/111069#Comment_111069

Hi Sir, here is a new question to ask.. What do I need to set to drip the fluid shape like picture 1 below:nActually, domain created (red colour) for the previous picture is assumed to be a vacuum.nHowever, I only able to get the initial state of the results (as shown in picture 2). Is it affected by the contact angle, surface tension, the diameter of the nozzle tip, or other conditions? Both are using the same value of the viscosity, density, and surface tension. The diameter of the nozzle tip is different in both cases.nnPicture 1:nPicture 2:nnn

[Rob]

We can model low pressure, but not vacuum: read up on the Knudsen Number and continuity. nTo create a region like the above you need to use a patch: this can be a register or predefined fluid region. n