Very good explanation. I have seen time and time again "converged" solutions but the solution kept changing with each iteration. Report definitions as a convergence criterion are a must
Hello! I ran a simulation where the energy residuals keep increasing but all the other residuals show decreasing trend. What might be the possible cause and solution of such trouble? After about 60 iterations, this happens.
Does time step affects solution in transient analysis? I am conducting a transient thermal-flow simulation which might take more than 60 mins of physical time to achieve steady state. Currently I am taking time step of 300 seconds(5 mins) with 300 iterations/time step. The velocity residuals reach lower than 1E-05 but energy and continuity residuals becomes steady at just below 1E-01. Is it acceptable or I need to change something? Please reply!
Hey Harsh, the time step needs to be small enough to capture the shortest transient phenomena in your simulation. If it is a conjugate heat transfer problem, the time step for solid needs to be much higher than fluids. You might want to check your flux to make sure they are being conserved, especially heat transfer if your energy residuals are high. Hope this helps!
For some reason it won’t let me open up convergence conditions. I double click on it and it doesn’t open and it also won’t let me select it from the residuals window.
Hi, you need to have a Report Definition first in order to define a convergence condition, you can see in the clip that Stephen has two created already when he opens the convergence conditions. Does that help?
Hi, integrated graphics cards usually share system RAM with your CPU, so your 16GB of system may practically end up as less. Ansys have not specifically tested that range of Graphics cards so it is hard to say, I would say it probably will run for small simulations, but you will definitely run into issues with larger models as you run out of RAM. Hope this helps!
![[CFD] Residuals in CFD (Part 1) - Understanding Residuals](http://i.ytimg.com/vi/v9OnNeYH4Ok/mqdefault.jpg)
![[CFD] Residuals in CFD (Part 1) - Understanding Residuals](/img/tr.png)
Thank you, Stephen for the quick demonstration. It is well described!
Very good explanation. I have seen time and time again "converged" solutions but the solution kept changing with each iteration. Report definitions as a convergence criterion are a must
Well explained, short and informative. Very good source of information!
Than You! It is really beneficial.
wow this is really usefull info. thanks!!
Great explanation, thank you so much. But I am unable to monitor the WSS plot. Can you give me some idea about this?
Hi , nice Explanation , could you explain how to create a report definition?
Thanks. This is very helpful !
Great video!. What is the difference between stop criteria for a particular parameter and global residuals?
thanks bro
Thank you 🙏
thank you soooo much.
How can I plot wall-shear rplot after simulation in ansys 17.2 ?
thank you sir!
What of the variable never stabilizes?
thank you
Very useful
Hello! I ran a simulation where the energy residuals keep increasing but all the other residuals show decreasing trend. What might be the possible cause and solution of such trouble?
After about 60 iterations, this happens.
Try for different solution model
Does time step affects solution in transient analysis? I am conducting a transient thermal-flow simulation which might take more than 60 mins of physical time to achieve steady state. Currently I am taking time step of 300 seconds(5 mins) with 300 iterations/time step. The velocity residuals reach lower than 1E-05 but energy and continuity residuals becomes steady at just below 1E-01. Is it acceptable or I need to change something? Please reply!
Hey Harsh, the time step needs to be small enough to capture the shortest transient phenomena in your simulation. If it is a conjugate heat transfer problem, the time step for solid needs to be much higher than fluids. You might want to check your flux to make sure they are being conserved, especially heat transfer if your energy residuals are high. Hope this helps!
For some reason it won’t let me open up convergence conditions. I double click on it and it doesn’t open and it also won’t let me select it from the residuals window.
Hi, you need to have a Report Definition first in order to define a convergence condition, you can see in the clip that Stephen has two created already when he opens the convergence conditions. Does that help?
Is the recent iris xe graphics with the 11th gen i5 16gb ram compatible and sufficient with ansys for medium 3d simulations?
Hi, integrated graphics cards usually share system RAM with your CPU, so your 16GB of system may practically end up as less. Ansys have not specifically tested that range of Graphics cards so it is hard to say, I would say it probably will run for small simulations, but you will definitely run into issues with larger models as you run out of RAM. Hope this helps!
1.8 million cells (poly cells) consume about 15-16gb of ram. If you are working with only 1M cells, 16gb will work fine.