Abstract
The soil-water is a major factor not only in the natural disaster such as landslides, but also in the preservation of the environment such as ground water recharge. Therefore, the soil-water movement is one of the urgent topics to be investigated in these fields. In the present paper, the methods of measuring soil-water velocity insite using the sinusoidal heat signal are developed.
First, the energy equation of flowing fluid is solved under the condition that the point heat source is heated sinusoidally. From the solution, two methods are developed, the amplitude-method and the phase-difference-method. The direction and the absolute value of the velocity are obtained by the former method. By the latter method, though only the absolute value of the velocity is obtained, deviation of the thermal diffusivity can be eliminated.
Second, the energy equation of the porous media as a model of the soil is developed introducing the two media, the flowing medium and the stationary medium, which play important roles in the conduction of heat. The obtained energy equation is similar to that of flowing fluid, so the fluid velocity in the porous media can be measured by the similar way.
Finally, the experiment of measuring the water velocity which is about 0.1-2.0mm/s in porous media is conducted by the phase-difference-method. The results agreed with the theoretical consideration, and the availability of the method to the soil-water velocity in site is confirmed.
