In recent years, the behaviour of subsurface water with a temperature gradient has generated considerable interest. Dynamic approaches to the phenomenon are founded on simultaneous mass and heat transport in porous media. Most problems are classified into two areas: one is natural and forced convection of fluids in saturated porous media and the other is such mass and heat transfer in unsaturated porous media, as encounterd in processes such as drying/vaporization, and pollutant migration.
Heat exchange between atmosphere and ground surface or between groundwater and soils/rock masses may generate new local flows and temperature gradients within the saturated zone. Thus, the heat transfer may make the analysis of groundwater flow more complicated because of addtional flow caused by non-uniform temperature distributions. Buoyancy effect caused by fluid density differences and exchange between fluid and solid phases are essential factors.
Moisture transfer with a temperature gradient induces heat transfer and changes in phase between liquid and vapor; therefore, it is very important to understand heat and moisture transfer in porous media to gain a better insight into unsaturated flow.
The basic theories of heat and fluid transfer in saturated and unsaturated soil are discussed in this chapter. Typical examples of heat and moisture transfer in closed and open systems are also presented.
KeywordsGroundwater Flow Moisture Transport Volumetric Water Content Moisture Transfer Mass Conservation Equation
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