The Effect of Anisotropic Permeability on the Temperature Profiles Obtained In a River Discharge Scenario to a Deep Aquifer

Abstract

- The discharge-recharge patterns between rivers and aquifers in soils are strongly influences by the degree of anisotropy in their hydraulic permeability. In consolidated soils, the ratio ‘horizontal/vertical’ permeabilities can reach values up to 10 and even more. As a consequence, as a result of the coupling between fluid flow and heat transport, the last caused by temperature boundary conditions, the temperature profiles turn also dependent of such anisotropy. In this paper, a typical river-aquifer scenario with permeable bottom is studied, searching both the flow patterns for different degree of anisotropy and the effect of the flow field in the temperatures vertical profiles. A harmonic temperature condition is applied to the soil surface while constant and different temperatures are imposed to the bottom of the aquifer and to the river. The coupled effect between flow and heat transport produces the formation of eddies of temperature in the form of thermal waves that displace to the up and down boundaries and to the right one due to the drag of the fluid. The mean temperature profiles tend to be lineal far from the river. The extension of the region where the profiles develop increase with the ratio ‘horizontal/vertical’ permeabilities. The problem is numerically solved by the network simulation method using the free software Ngspice.