Velocity streamlines in Fluent

raghuramswaroop · June 22, 2018, 06:08

I am trying to simulate the coolant effect on a tool insert and doing it in Fluent. The velocity streamlines are un-distorted even though the coolant is passing through the tool. What might be the problem? The velocity streamline I am getting is showing as straight lines.

RaiderDoctor · June 22, 2018, 10:39

Hi, could you post a picture of the results you are getting? It'll help us better understand what your issue is. Also, a brief description of your setup would also be appreciated.

raghuramswaroop · June 22, 2018, 11:19

In fluent setup, I used the upper surface of the box(fluid zone) as fluid inlet (velocity inlet boundary condition) and lower as fluid outlet (pressure outlet). Mentioning inlet pressure and outlet pressure as 1 bar. And for the remaining walls as symmetry boundary condition.

RaiderDoctor · June 22, 2018, 11:31

Okay, but that's still not enough to go on. Can you please post a picture of the results?

raghuramswaroop · June 22, 2018, 11:36

I am sharing a link of the images here. It is the temperature contour and velocity streamline.

https://drive.google.com/open?id=1pA...2wyrYRpKg6_K36

https://drive.google.com/open?id=1Ld...Ou5SlrcekUihnf

RaiderDoctor · June 22, 2018, 12:17

I'm starting to understand, but I'm going to need more info. Is this a transient or steady-state simulation? Also, I know you set the walls of your fluid domain to be Symmetry (I'm guessing to avoid the non-slip condition) but what about the walls of your part? What are they set to? Also, is this a FSI? What are your convergence criteria, and did you model correctly converge?

raghuramswaroop · June 22, 2018, 15:19

It is a steady state analysis. Yes, you are right. I opted for no-slip condition for the solid walls also. Only the inlet and outlet matters in this project. Walls of the part are simply walls. There are totally 6 walls and one tool tip. Tool tip has a very small surface where I give 1090K temperature. Attached is the image in which you can see how I defined the wall of my tool. Also can you tell me what is meant by free stream temperature in the convection part ?

https://drive.google.com/open?id=1XO...fVVS1I_iz-DEt5

RaiderDoctor · June 22, 2018, 15:38

So, if this is a steady-state analysis, could you explain why you are only using 30 iterations? That seems really low for simulation such as this, provided that your residuals are converging.
You say that you used the no-slip on the solid walls also. I'm going assume that you mean the walls of your tool are no-slip, while the symmetry walls are slip, right?
The picture looks a little odd to me, because your Momentum tab is greyed out. Usually, this is why you can specify things like Wall Motion and Shear Condition and the like. With it being greyed out, does that mean that you are setting those quantities with another option?
As to your final question, I'm not sure, unfortunately. I would click the Help button shown in your picture to learn more about it.

raghuramswaroop · June 22, 2018, 15:59

This is my first time using fluent and also ansys. I just gave a random number of 30. Walls of the box just act as boundary and they don't have any role in the simulation, I am assuming in that way. Walls of the tool are not getting the momentum tab highlighted. I don't know why. I guess the program is deciding it. As the tool doesn't move, it is fine for me even if I don't get momentum tab.

RaiderDoctor · June 22, 2018, 19:15

Fluent isn't especially easy for first time users - nearly everyone here understands that haha. Could you post a picture of your residuals, let's see if they converged.

raghuramswaroop · June 23, 2018, 06:23

My ANSYS university server is down at the moment. I will post pictures as soon as the server is set right.

raghuramswaroop · June 25, 2018, 08:35

Hello. Just now the server is up. Here is the picture of residuals. You can have a look at it.

https://drive.google.com/open?id=16O...57kh0Irdb7lq2n

RaiderDoctor · June 25, 2018, 13:10

These aren't exactly what I was talking about. These are your convergence criteria, under the Residual Monitor menu. Click Plot to actually show how your residuals are changing over the course of the simulation.

raghuramswaroop · June 25, 2018, 17:16

Yes. I have done the plot and it is as below. I am concerned only about the temperature change. But I am getting the initial temp and final temp of the tool as the same.

Below are the pictures of residual plot and temp change.

I need to get the temperature contour and velocity streamline correctly. I have been doing for one month now but not fruitful.

https://drive.google.com/open?id=1jT...JedtMkZQBpK8Jz

https://drive.google.com/open?id=1jd...5HLPzCgRgs1v2V

RaiderDoctor · July 4, 2018, 11:57

It makes sense that the initial and final temperatures are the same, as the solution is not fully converged. Even though it looks like the residuals are not really changing, it's easy to observe small differences from one iteration to the next. What I would recommend trying is increasing your Under-Relaxation Factors to a higher quantity (maybe 1?) and see if that helps your convergence at all. While you are at it, drastically increase the number of iterations (try at least 200) and see how long it takes to converge. The eventual goal is to get your solution to converge quickly with very little iterative effort, so you can save on efficiency. However, you need to set your simulation up correctly first, though.

raghuramswaroop · July 4, 2018, 15:34

Yes. I did it. I increased the values of Under relaxation factors and simulated it. Still getting the same result.

Picture of the under-relaxation factors.

https://drive.google.com/open?id=1aa...w880rG4PpyrSET

June 22, 2018, 06:08	Velocity streamlines in Fluent	#1
raghuramswaroop New Member Swaroop Join Date: Apr 2018 Posts: 21 Rep Power: 8	I am trying to simulate the coolant effect on a tool insert and doing it in Fluent. The velocity streamlines are un-distorted even though the coolant is passing through the tool. What might be the problem? The velocity streamline I am getting is showing as straight lines.

June 22, 2018, 10:39		#2
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 10	Hi, could you post a picture of the results you are getting? It'll help us better understand what your issue is. Also, a brief description of your setup would also be appreciated. raghuramswaroop likes this.

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June 22, 2018, 11:19		#3
raghuramswaroop New Member Swaroop Join Date: Apr 2018 Posts: 21 Rep Power: 8	In fluent setup, I used the upper surface of the box(fluid zone) as fluid inlet (velocity inlet boundary condition) and lower as fluid outlet (pressure outlet). Mentioning inlet pressure and outlet pressure as 1 bar. And for the remaining walls as symmetry boundary condition.

June 22, 2018, 11:31		#4
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 10	Okay, but that's still not enough to go on. Can you please post a picture of the results?

June 22, 2018, 11:36		#5
raghuramswaroop New Member Swaroop Join Date: Apr 2018 Posts: 21 Rep Power: 8	I am sharing a link of the images here. It is the temperature contour and velocity streamline. https://drive.google.com/open?id=1pA...2wyrYRpKg6_K36 https://drive.google.com/open?id=1Ld...Ou5SlrcekUihnf

June 22, 2018, 12:17		#6
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 10	I'm starting to understand, but I'm going to need more info. Is this a transient or steady-state simulation? Also, I know you set the walls of your fluid domain to be Symmetry (I'm guessing to avoid the non-slip condition) but what about the walls of your part? What are they set to? Also, is this a FSI? What are your convergence criteria, and did you model correctly converge?

June 22, 2018, 15:19		#7
raghuramswaroop New Member Swaroop Join Date: Apr 2018 Posts: 21 Rep Power: 8	It is a steady state analysis. Yes, you are right. I opted for no-slip condition for the solid walls also. Only the inlet and outlet matters in this project. Walls of the part are simply walls. There are totally 6 walls and one tool tip. Tool tip has a very small surface where I give 1090K temperature. Attached is the image in which you can see how I defined the wall of my tool. Also can you tell me what is meant by free stream temperature in the convection part ? https://drive.google.com/open?id=1XO...fVVS1I_iz-DEt5

June 22, 2018, 15:38		#8
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 10	So, if this is a steady-state analysis, could you explain why you are only using 30 iterations? That seems really low for simulation such as this, provided that your residuals are converging. You say that you used the no-slip on the solid walls also. I'm going assume that you mean the walls of your tool are no-slip, while the symmetry walls are slip, right? The picture looks a little odd to me, because your Momentum tab is greyed out. Usually, this is why you can specify things like Wall Motion and Shear Condition and the like. With it being greyed out, does that mean that you are setting those quantities with another option? As to your final question, I'm not sure, unfortunately. I would click the Help button shown in your picture to learn more about it.

June 22, 2018, 15:59		#9
raghuramswaroop New Member Swaroop Join Date: Apr 2018 Posts: 21 Rep Power: 8	This is my first time using fluent and also ansys. I just gave a random number of 30. Walls of the box just act as boundary and they don't have any role in the simulation, I am assuming in that way. Walls of the tool are not getting the momentum tab highlighted. I don't know why. I guess the program is deciding it. As the tool doesn't move, it is fine for me even if I don't get momentum tab.

June 22, 2018, 19:15		#10
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 10	Fluent isn't especially easy for first time users - nearly everyone here understands that haha. Could you post a picture of your residuals, let's see if they converged.

June 23, 2018, 06:23		#11
raghuramswaroop New Member Swaroop Join Date: Apr 2018 Posts: 21 Rep Power: 8	My ANSYS university server is down at the moment. I will post pictures as soon as the server is set right.

June 25, 2018, 08:35		#12
raghuramswaroop New Member Swaroop Join Date: Apr 2018 Posts: 21 Rep Power: 8	Hello. Just now the server is up. Here is the picture of residuals. You can have a look at it. https://drive.google.com/open?id=16O...57kh0Irdb7lq2n

June 25, 2018, 13:10		#13
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 10	These aren't exactly what I was talking about. These are your convergence criteria, under the Residual Monitor menu. Click Plot to actually show how your residuals are changing over the course of the simulation.

June 25, 2018, 17:16		#14
raghuramswaroop New Member Swaroop Join Date: Apr 2018 Posts: 21 Rep Power: 8	Yes. I have done the plot and it is as below. I am concerned only about the temperature change. But I am getting the initial temp and final temp of the tool as the same. Below are the pictures of residual plot and temp change. I need to get the temperature contour and velocity streamline correctly. I have been doing for one month now but not fruitful. https://drive.google.com/open?id=1jT...JedtMkZQBpK8Jz https://drive.google.com/open?id=1jd...5HLPzCgRgs1v2V

July 4, 2018, 11:57		#15
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 10	It makes sense that the initial and final temperatures are the same, as the solution is not fully converged. Even though it looks like the residuals are not really changing, it's easy to observe small differences from one iteration to the next. What I would recommend trying is increasing your Under-Relaxation Factors to a higher quantity (maybe 1?) and see if that helps your convergence at all. While you are at it, drastically increase the number of iterations (try at least 200) and see how long it takes to converge. The eventual goal is to get your solution to converge quickly with very little iterative effort, so you can save on efficiency. However, you need to set your simulation up correctly first, though.

July 4, 2018, 15:34		#16
raghuramswaroop New Member Swaroop Join Date: Apr 2018 Posts: 21 Rep Power: 8	Yes. I did it. I increased the values of Under relaxation factors and simulated it. Still getting the same result. Picture of the under-relaxation factors. https://drive.google.com/open?id=1aa...w880rG4PpyrSET