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Full-field modeling of heat transfer in asteroid regolith 2: Effects of porosity

Ryan, Andrew J. and Pino-Muñoz, Daniel and Bernacki, Marc and Delbo, Marco and Sakatani, Naoya and Biele, Jens and Emery, Joshua P. and Rozitis, Benjamin (2022) Full-field modeling of heat transfer in asteroid regolith 2: Effects of porosity. . (Unpublished) https://resolver.caltech.edu/CaltechAUTHORS:20220214-396468100

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Abstract

The thermal conductivity of granular planetary regolith is strongly dependent on the porosity, or packing density, of the regolith particles. However, existing models for regolith thermal conductivity predict different dependencies on porosity. Here, we use a full-field model of planetary regolith to study the relationship between regolith radiative thermal conductivity, porosity, and the particle non-isothermality. The model approximates regolith as regular and random packings of spherical particles in a 3D finite element mesh framework. Our model results, which are in good agreement with previous numerical and experimental datasets, show that random packings have a consistently higher radiative thermal conductivity than ordered packings. From our random packing results, we present a new empirical model relating regolith thermal conductivity, porosity, temperature, particle size, and the thermal conductivity of individual particles. This model shows that regolith particle size predictions from thermal inertia are largely independent of assumptions of regolith porosity, except for when the non-isothermality effect is large, as is the case when the regolith is particularly coarse and/or is composed of low thermal conductivity material.


Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription
https://doi.org/10.1002/essoar.10510465.1DOIDiscussion Paper
https://github.com/msbentley/aggregateRelated ItemCode
https://doi.org/10.5281/zenodo.5839026DOIData
ORCID:
AuthorORCID
Ryan, Andrew J.0000-0002-7535-8416
Delbo, Marco0000-0002-8963-2404
Biele, Jens0000-0002-7414-829X
Emery, Joshua P.0000-0001-9265-9475
Rozitis, Benjamin0000-0001-9893-241X
Additional Information:The copyright holder for this preprint is the author/funder. Published Online: Sat, 12 Feb 2022. This work was primarily funded by NASA Solar System Workings Grant 80NSSC21K0146. The authors acknowledge support from the Academies of Excellence on Complex Systems and Space, Environment, Risk and Resilience of the Initiative d’EXcellence (IDEX) Joint, Excellent, and Dynamic Initiative (JEDI) of the Universite Cote d’Azur as well as from the Centre National d’Etudes Spatiales (CNES). B.R. acknowledges funding support from the UK Science and Technology Facilities Council (STFC). This material is based in part upon work supported by NASA under Contract NNM10AA11C issued through the New Frontiers Program. We thank Ron Ballouz for sharing his code for generating sphere packings using the method by Ringl et al.v (2012). We also thank Mark Bentley for making his aggregate packing code publicly available on his GitHub page (https://github.com/msbentley/aggregate). The portion of the aggregate code that we modified to include periodicity is available in an external archive, along with our model geometry/solution files, script for processing model outputs, and a summary calculation spreadsheet (Ryan, 2022; https://doi.org/10.5281/zenodo.5839026). The authors declare no real or perceived conflicts of interest.
Funders:
Funding AgencyGrant Number
NASA80NSSC21K0146
Universite Cote d’AzurUNSPECIFIED
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
NASANNM10AA11C
DOI:10.1002/essoar.10510465.1
Record Number:CaltechAUTHORS:20220214-396468100
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20220214-396468100
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113436
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:14 Feb 2022 19:20
Last Modified:25 Jul 2022 23:14

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