Problem with 3weeks Day2

momentumv · July 2, 2019, 18:00

I tried to follow the Tutorial in the 3 week course, and on day2 it has Turtorial Three from http://cfd.at/downloads/FoamTutV4_3-ExampleThree.pdf.

The example ran fine until I tried to change the mesh density to 100 cells (as suggested by the tutorial), and then it solves up to time step 0.00459 when it crashes with a Negative initial temperature T0: -13.1838

Not sure what the issue is.

momentumv · July 2, 2019, 18:04

**Edit** this was because I was comparing the 1 bar that I ran to the 10 bar that was reported. ***/edit**** I also was getting max Courant numbers of half that reported by the tutorial pdf.

momentumv · July 2, 2019, 18:12

Increasing the time step for the solution from 1 e-5 to 1 e-4 solves the problem, but I don't understand why a very small courant number would lead to unstable Temperatures causing the crash.

July 2, 2019, 18:00	Problem with 3weeks Day2	#1
momentumv New Member Join Date: Jan 2015 Posts: 7 Rep Power: 11	I tried to follow the Tutorial in the 3 week course, and on day2 it has Turtorial Three from http://cfd.at/downloads/FoamTutV4_3-ExampleThree.pdf. The example ran fine until I tried to change the mesh density to 100 cells (as suggested by the tutorial), and then it solves up to time step 0.00459 when it crashes with a Negative initial temperature T0: -13.1838 Not sure what the issue is.

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July 2, 2019, 18:04		#2
momentumv New Member Join Date: Jan 2015 Posts: 7 Rep Power: 11	Edit this was because I was comparing the 1 bar that I ran to the 10 bar that was reported. */edit** I also was getting max Courant numbers of half that reported by the tutorial pdf.

July 2, 2019, 18:12		#3
momentumv New Member Join Date: Jan 2015 Posts: 7 Rep Power: 11	Increasing the time step for the solution from 1 e-5 to 1 e-4 solves the problem, but I don't understand why a very small courant number would lead to unstable Temperatures causing the crash.