Discussion Forum

Hi,

I'm currently working on simulating the degree of saturation variation in compacted pavement layer during solar dry back process. A small scale outdoor experiment was undertaken to measure the degree of saturation variation in the pavement layer under solar radiation for 3 days period. then I am trying to validate the experimental results with the Comsol simulation results.

I have modelled the 300mm thick pavement layer and subgrade in a 1D workspace. I am coupling 'heat transfer with surface to surface radiation' and 'moisture transport in porous media'. I dont have any information about evaporation rate during 3days period. But i have the ambient conditions data for every 5minutes (eg., temperature,humidity,windspeed, solar radiation). So I used those data as a boundary condition in both heat and moisture transfer physics (Moisture and heat fluxes).

But I could only see the degree of saturation variation at the surface and the variations are unrealistic below 25mm from the surface of the pavement layer. I couldn't figure out the reasons for that. Also, the temperature at the surface is less than the bottom layers throughout the 50 hours period of simulations.

How can I fix this? . are these issues related with wrong selection of physics to study the evaporation in porous media? The model is attached here.

Thank you Gopoojithaa