WUFI

Is it possible to take into account the snow on the ground in WUFI 2D? I plan to make simulations about frost penetration in the ground. Snow is an important heat insulation material but the problem is that the snow thickness varies during the year. Sometimes snow even disappears here in Finland .

One possibility is to include the effect of snow into the heat transfer coefficient, making it a variable depending on the snow thickness. But there is also another issue: snow is melting by the heat coming from the ground. In that case the ground surface temperature stays at zero degrees centigrade. It means that the boundary condition type will change.

Can you help?

Hello Jorma,
I made some thoughts about snow as well. The first problem over here is, that we have no information on the snow laying on the ground in the weather data. All we have is the melted snow (rain).
Second problem is, that there is no possibility to change the heat transfer coefficient during the calculation.

But you can try to do it another way:
You can start the calculation without snow until the first snow is laying on the surface. Then you finish the calculation and export the temperature and relative humidity out of WufiMotion.
These two files you can use as start conditions for your next calculations, where you change the boundary conditions and the climate file. Create a climate file with the conditions on the surface (for example temperature = 0 and RH is 100 all the time) and include it with a quite high heat transfer coefficient (eg 1e7). Please do not change the grid of the resuming calculation, it will not work...
Then after calculating the snow period, you again extract the conditions in the construction and use them as start conditions for the snow less period.

Another way may be to include the snow as a layer, but i think it´s quite tricky to find the right physical properties. The change in the temperature can maybe be simulated using the parameters for PCM-materials like the temperature dependent thermal conductivity or the enthalpy...

The translucency of the snow may be simulated using a heat source with a percentage of the solar radiation.

Please inform me, if you get the snow simulated somehow, i´m very interested in that.

Hope that gives you food for thoughts,
Greetings,
Christian