[mumtaz ersan]

Hello everyone,

First off all i am new at this forumsite and cfd analysis...

I want to ask about flowtrajectories in solidworks flowsimulation, i ask it in this main CFD Forum because i search software user's forum for solidworks but i can't find. I hope it isn't wrong...

I analyze pipe in flowsimulation which is inner dia 3,25 mm. , outer dia is 19 mm..

When i viewing the results, i realized that some vortex is created,

I select the line for flow trajectories at number 20 and 5 of them become vortex,
When i select the trajectories at number 100, maybe 30 of them become vortex , the other lines is linear...

What does this result mean?? For example; can i say that %20 fluid is vortex the other part of fluid is linear????

Or can i say that %30 fluid is vortex????? Or this trajectories are only for visualization , i can't get result volume ratio of vortex...

I hope , i can explain my ques.,

Thanks everyone....

[Boris_M]

Hi Mehmet,

you are lucky I saw your post here. If you want to get answers on SWFS you should post here:
http://www.cfd-online.com/Forums/flo...orks-flotherm/

SWFS is developed by Mentor Graphics and sold by SW as SWFS and sold in other CAD intergations by Mentor Graphics as FloEFD but with some more capabilities.

I cannot tell what type of pipe you have that you get a vortex inside the pipe. But if you select a line and a certain number of trajectories, then they will be distributed equally over the length of the line. It doesn't necessarily tell how much is a vortex and how much is not.

Could you tell what your plan is so that I can better understand what you are trying to get out of your simulation. Maybe there is another way of getting that information.
Can you post a picture of the vortex and the pipe?

Boris

[mumtaz ersan]

First of all , Thanks for answer and interest, After this post , i will be more carefull about which forum i am asking or posting

Attachment 35533

actually i draw connector which's inlet dia. 3,25 mm. outlet dia is 19 mm.,
flow is pass through from my connector to flow sensor,At the attachment pic. nr1 is vortex and nr. 2 is flow sensor...

after activate simulation with 20 lines there is no vortex while air is passing flow sensor area. but with 80 lines it shows me vortex on flow sensor So what i have to do there , i have to take precautions for vortex or can i say that there will be no vortex because program doesn't show me vortex with 20 lines

[mumtaz ersan]

i hope i can succes to upload to pic.

Ads?z.jpg

[Boris_M]

Oh no, Don't misunderstand that if the trajectories don't show a vortex, that there is non. Trajectories are just mass less particles and show how the flow is moving by simply following the velocity vectors beginning where the trajectory starts. Now if that particle doesn't get into a vortex then you don't see one but that does not mean that there is no vortex. It just means that this partcile will not get into a vortex by following the flow from the point where it started. Another particle from a nother point might get into that vortex.
A very simple but dangerous example. You are standing at a street and want to cross the street on foot. Now just because you can cross it without been hit by a car does not mean that there are no cars on the street. If you would have crossed the street 100m further down the road, a car might have hit you because it would have been much closer to you.
Another example: You are standing 5m away from a wall of a building with your eyes shut and throw a stone at the wall. The stone hits the wall and falls to the ground. Now just because you didn't hit a window does not mean tere is no window. If you would have been 3m to the right and thrown the stone exactly the same way and hit the wall at exactly the same height then you would have hit the window.

So the Trajectories only show how the flow is moving through the model but only from that point where the line starts. At a different starting point the line would move differently and if you for example have to outlets, the flow from the one starting point would leave the outlet 1 and from the other starting point it would leave outlet 2.

If you really want to know where a vortex is along your line so along the plane this line lies on then you should use a Cut Plot. This is just a 2D cut though the model at that location so again if you move the plot out of that plane or into another angle, the flow in that plane will most likely look different.
In the cut plot you can show vectors or stream lines and LIC to visualize the flow and if you use the velocity component which is along your main flow direction as parameter such as "velocity (x)", you can see the positive velocity in positiv "x" direction and negative velocity in negative "x" direction. If you then for example set min and max values to -1m/s and +1m/s and reduce the colors to 2 colors you will see where the flow is in positive direction by red and negative direction by blue colors. So in a vortex the flow in your case should be coming towards the inlet after the step to the larger diameter as this is a very strong step which will create a vortex with backflow.

Boris

[mumtaz ersan]

Thanks for explanation, now i understand better...