Monday, November 13, 2006 - 1:15 PM
82-1
Numerical Evaluation of the Heat Pulse Probe for Changing Geometries.
Hirotaka Saito, University of California, Riverside, Environmental Sciences, Riverside, CA 92521, Jirka Simunek, Environmental Science, Bourns Hall A135 U.of CA Riverside, Riverside, CA 92521, Atac Tuli, University of California at Davis, Davis, CA 95616, and Jan Hopmans, U.of CA-Davis, Land Air Water Res., 123 Veihmeyer Hall 1 Shields Ave, Davis, CA 95616, United States of America.
The heat pulse probe (HPP) has increasingly received attention over the last decade as it allows in-situ, direct, simultaneous, and automated measurements of soil hydraulic and thermal properties and soil water flux. Although the developments to date show significant applications, changes in HPP design and operation are needed to increase the sensitivity to smaller water fluxes. In this study, numerical simulations were used to evaluate the effects of 1) thermal properties of HPP sensor materials, 2) heater size, 3) heat pulse intensity, and 4) vapor flow on temperature responses. All numerical experiments were conducted using the HYDRUS-2D code, extended to allow for coupled movement of liquid water, vapor, and heat. The sensitivity study shows the potential benefits of shorter thermistor needles and larger diameter heater needles that allow larger heat pulses, thereby increasing measurement sensitivity to lower water fluxes, provided that the latent heat of vaporization is taking into account.