Learning Forum

[malin.genau]

Hello everyone,

I would like to simulate the heat loss through the base slab or basement of a building under varying groundwater table depths and groundwater flow velocities using Ansys Fluent. In this context, I aim to model the unsaturated zone above the groundwater table in a physically meaningful way.

In particular, this unsaturated zone should represent realistic hydrothermal behavior, including heat and moisture transport. Ideally, the model should account for processes described by equations such as the Richards equation, i.e. a time-dependent variation of pore water saturation and hydraulic conductivity, for example due to precipitation or seasonal effects.

My main question is:

How can the unsaturated zone above the groundwater table be modeled in a realistic manner within the capabilities of Ansys Fluent?

Are there recommended modeling approaches (e.g. porous media models, multiphase flow models, or user-defined functions) to represent variable saturation and coupled heat and moisture transport in this zone?

Thank you very much in advance for your support.

[Rob]

What exactly is the mechanism that you want to replicate? Ground water movement tends to be slow, so how much convection are you expecting relative to thermal conduction? 

Multiphase models tend to be transient, so domain size and time scales become time/cpu expensive. Porous media could work well, but aren't designed to hold water in a geological sense (I get good lessons on that from my garden - topsoil, clay and mud stone shale with thin coal/ganister seams).