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ID Project Category View Status Date Submitted Last Update 0003136 OpenFOAM Bug public 2018-12-18 12:46 2019-01-28 17:40 gs78 henry high major always resolved fixed linux Ubuntu 18.04 0003136: Wrong dynamic viscosity computed for the liquid nitrogen I am using the sprayFoam solver to investigate the liquid nitrogen injection into a chamber. Thus I am using the tutorial available for the sprayFoam solver by setting up the liquid nitrogen (N2) instead of the n-heptane (C7H16) initially. After running the simulation, I have a dynamic viscosity in a range of 1e+24 Pa.s whereas this from the NIST database for instance is in a range of 1e-6 Pa.s Thus I have checked the dynamic viscosity computed in the liquid library in OpenFOAM. To compute this physical variable, OpenFOAM uses a function related to the temperature and also related to 5 coefficients from a to e. Afterwards, I have compared these coefficients to those from other fluids to see if there is any difference. The only difference I have seen is for the coefficient "a" which is always negative except for the liquid nitrogen. Thus I have corrected the coefficient a by adding a minus. (-32.165 instead of 32.165 initially). After recompiling the library and running again the simulation I have the dynamic viscosity in a good range. Thus I suggest to change the coefficient a (32.165) to -32.165 I have provided two graphs. The first graph on the left side is the original dynamic viscosity computed by OpenFOAM by using the NRSDS function number 1 (mu=exp(a+(b/T)+c*ln(T)+d(T^e)) for a temperature range from 100K to 126.1 K. The second graph on the right side is the corrected dynamic viscosity for the same temperature range by changing the coefficient a and by comparing the values with the NIST database. The only gap between both curves is that I do not know at which pressure the initial dynamic viscosity in OpenFOAM has been computed. No tags attached.

#### Issue History

Date Modified Username Field Change
2018-12-18 12:46 gs78 New Issue
2018-12-18 12:46 gs78 File Added: Dynamic viscosity report.png
2018-12-18 14:53 henry Note Added: 0010224
2018-12-18 15:22 gs78 Note Added: 0010225
2018-12-18 16:29 henry Note Added: 0010227
2018-12-18 17:00 gs78 Note Added: 0010228
2018-12-18 17:28 henry Note Added: 0010229
2018-12-18 17:37 gs78 Note Added: 0010230
2018-12-18 17:50 henry Note Added: 0010231
2018-12-19 12:58 gs78 Note Added: 0010233
2019-01-24 09:39 gs78 File Added: IMG_2204.JPG
2019-01-24 09:39 gs78 File Added: IMG_2205.JPG
2019-01-24 09:39 gs78 Note Added: 0010262
2019-01-24 10:39 gs78 Note Added: 0010263
2019-01-24 14:26 henry Note Added: 0010264
2019-01-25 14:53 gs78 File Added: Liquid density comparison.png
2019-01-25 14:53 gs78 File Added: Liquid dynamic viscosity comparison.png
2019-01-25 14:53 gs78 File Added: Liquid heat capacity comparison.png
2019-01-25 14:53 gs78 File Added: Liquid thermal conductivity comparison.png
2019-01-25 14:53 gs78 Note Added: 0010265
2019-01-28 17:40 henry Assigned To => henry
2019-01-28 17:40 henry Status new => resolved
2019-01-28 17:40 henry Resolution open => fixed
2019-01-28 17:40 henry Fixed in Version => 6
2019-01-28 17:40 henry Note Added: 0010267