Learning Forum

[adc430]

Hi all, I asked for advice earlier however i felt maybe i should get help from the very beginning. First time using ansys and i have a project using the program. The objective is to create a fluid flow that will cool a heart to a certain temperature and i have to determine a water temperature to use. i have the CAD model all set however i cant figure out the software part. I understand that i need to use the internal volume of the jet system to use on ansys however i have tried every method i know. i tried the 'delete face' option and didn't work so i am looking for help/opinions/resources that can help me. Really appreciate it. (using solidworks 2013 and ansys 16)

[Keyur Kanade]

you can do it in spaceclaim. 

see following video. 

https://www.youtube.com/watch?v=1LBPLfs3QSo

 

[adc430]

Thanks for the reply but I don't have access to Spaceclaim, only have access to solidworks. Any other suggestions?

[Keyur Kanade]

if you want to do it solidworks then you may need to contact solidworks support. 

ansys academic version has spaceclaim with it. you can download student version. 

/forum/forums/topic/download-2019-r1-student-products/

 

[adc430]

Can I import the solidwork assembly (or part) into spaceclaim?

[Rob]

Yes, but you may need to use STEP or similar to transfer the files: the full version has a reader but I'm not sure about the Student version. 

Remember, for CFD we need the fluid space, so all of the pipe internals and space around the heart. I'm assuming the image above also has an outer casing?

[adc430]

Yes it is the outer casing. The goal is to generate a flow around the heart

[peteroznewman]

I see 12 pipes that point inward to a central volume. All the pipes are horizontal arranged along the diagonal of the four vertical faces of some rectangular space.

Is there a rectangular tank that is not shown?  Are all 12 pipes inlets to that tank?  If so where is the drain? Are some of them outlets? Is the tank filled with liquid and the 12 pipes bring in more liquid, or is the tank just air and the liquid jets out of the pipes in a stream toward the heart. Please explain.

If the heart is supported in a tank filled with a liquid, how deep is the liquid in that tank.  Is there a free surface of the liquid with air above, or does the tank have a top and is fully filled with liquid? Please explain.

From the point of view of a CFD model for cooling the heart, you don't need all the piping. You just need the tank with the 12 openings in the four side walls.

[adc430]

Yes there is a empty tank (suppressed for better visual) that the heart is settled in. The tank contains 12 inlets in which jet a fluid towards the heart, cooling it, and naturally falling to the bottom of the tank that contains outlets in which the tank will be drained (and goes thru another process but not important).

Thank you for the information, this is the first time I use the software with no help from professors so I'm not sure what do to and need extra help. So all I have to do is use the tanks inlets and outlet and use the inner walls as my boundary wall?

[peteroznewman]

Okay, now the model you want to build is clearer and I hope the CFD experts will chime in. I am not a CFD expert but I will tell you what I know.

You need to construct a rectangular tank solid volume. You need a heart solid inside that volume. You need to subtract the heart from the tank so there is a heart-shaped void in the tank solid. You need to imprint 12 circles on the four side faces of the tank solid. These faces will be the inlet to the fluid, let's call that water. If you don't care about the fluid after it falls off the heart, then the bottom face of the tank solid will be the outlet.

The tank solid (with the heart shaped hole in the center) will be meshed with cells. Each cell will represent the fraction of water in that cell. This is called a VOF model. At the beginning of the simulation, all the cells will have an air fraction of 1, the tank is filled with air. The 12 circles on the walls will have an air fraction of 0 (they will be water), and they will have an inlet velocity (or some flow rate definition). The side walls of the tank and the surface of the heart will all be walls (except for the 12 inlet faces). The top face of the tank can be a pressure outlet.

Here is some more information.

It will be a transient simulation. Get ready to do a lot of waiting...

https://www.youtube.com/watch?v=73c4ojTW7Hw

 

[adc430]

So I have to create a cavity or mold of the heart inside the box making the distance between the inlet and the heart as a solid? And also, does that mean the Andy's simulation is not going to be a fluid flow (fluent) but a thermal transient analysis?

[adc430]

Update: This is the model i currently have. As stated, the side jets shoot water to the heart that will cool it. I'm completely lost as to how to proceed (sorry for any inconvenience, but since I've never touched the software before this I have no idea what to do). 

[peteroznewman]

You have to stop thinking about the mechanical parts, like the tank walls which you have created above. The thickness of the tank wall is irrelevant.

You have to start thinking about the computational domain, which is a rectangular solid with a heart-shaped cavity at the center and three circular faces on each of the four sides of the rectangle.   There is a second solid, the heart, at the center, filling the cavity.

You construct this domain by drawing a rectangular block around the heart, then do a boolean subtract of the heart from the block.  Then you have to imprint the three circles on each side face.  If you don't know how to do that in SW, you can do that in DesignModeler.

Make the rectangular block and leave the heart in the center. In SolidWorks, do File, Save As and choose file type Parasolid.  Start ANSYS Workbench, in the toolbox on the left are Analysis Systems, then below that Components.  There is a Geometry component. Drag that out and drop it on the Project Schematic. If you are on an old version of ANSYS, when you double click that, it will start DesignModeler.  Once that starts, use File, Import External Geometry File and point to the Parasolid file, then click Generate.

If you get that far, you can create a Workbench Project Archive .wbpz file by doing File, Archive.  You can attach that file to your post AFTER you have clicked Add Post, an Attach button will appear, then you can point to the .wbpz file and upload it to the site.

Here's another idea, create a 2D version of this model first. 2D models must be drawn on the XY plane.  You need two sheet bodies (surfaces), one for the heart and one for the air/water around the heart. In this case, it might be simpler to have the three pipe stubs coming out of the side of the rectangular computational domain. The reason to make a 2D model is that it will solve much, much faster, so you will be waiting for tens of minutes instead of tens of hours to see a result, but all the physics you need will be represented in the 2D model.