Monte Carlo Modeling of the Thermal Conductivity of Porous Ice

Details Monte Carlo Modeling of the Thermal Conductivity of Porous Ice Monte Carlo Modeling of the Thermal Conductivity of Porous Ice

Dec 1999

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999baas...31.1588p&link_type=abstract

American Astronomical Society, DPS Meeting #31, late abstracts, #59.28; Bulletin of the American Astronomical Society, Vol. 31,

Statistics

Computation

Scientific paper

The thermal conductivity of low temperature ice has been derived both experimentally and by theoretical considerations. The formulae provided by Klinger (1980, 1981) have gained widespread use. But cometary material is highly porous and, although it is certain that porosity lowers the thermal conductivity, it is unclear to what extent, and how does the correction depend on porosity and on the pore size distribution. So far, answers to these questions have been either vague or widely discrepant. Early estimates of the effect of porosity (p) on the thermal conductivity (K) of cometary ice were based on purely geometrical considerations, yielding correction factors of order unity. Later work included the 'Hertz factor', the reduced area of contact between grains, which resulted in a much (orders of magnitude) lower correction factor. Attempts to determine the 'Hertz factor' by fitting laboratory data yielded a rather wide range of values, between 0.1 and 0.001. All these corrections are temperature independent. However, the correction due to porosity should also depend on temperature (T), since heat may be transferred through the pores by radiation. In order to obtain the desired relation K(T,p), we adopt a 3-D Monte Carlo procedure. This procedure has the advantage that, given the bulk conductivities of the constituents, the conductivity of the medium can be modeled as a function of both porosity and temperature. The basic structure assumed is fractal, with the pore size distribution spanning several orders of magnitude. Obviously, in order to model such a structure a very fine 3-D grid would be required, so as to accommodate the smallest and largest voids. Such an approach is impractical (impossible, in fact, in view of computational constraints!). In order to circumvent this difficulty, we adopt a hierarchical procedure. We find that the thermal conductivity is lowered by several orders of magnitude at high porosities; in addition it is strongly dependent on temperature (increasing with increasing temperature), but it is almost scale-independent.

Affiliated with

Also associated with

No associations

Rating

Monte Carlo Modeling of the Thermal Conductivity of Porous Ice does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Monte Carlo Modeling of the Thermal Conductivity of Porous Ice, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Monte Carlo Modeling of the Thermal Conductivity of Porous Ice will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1724854