Thermally induced countercurrent flow in unsaturated rock

Abstract

Axial temperature gradients were established in two sealed unsaturated rock cores and maintained until near steady distributions of temperature and moisture content were observed. Water content measurements, made at intervals along the length of the cores, indicated net moisture movement was from warm to cold. Water content measurements during a preliminary experiment with an unsaturated sand column also indicated net moisture movement was from warm to cold. Changes in the distribution of a tracer introduced into one of the rock cores and the sand column indicated liquid movement from cold to warm had occurred. The magnitude of the water content changes was greater and the time required to reach near steady-state conditions was shorter for a more permeable, porous sandstone core than for a welded tuff core. The water content decreased to zero near the hot end of the sand column.