Involve: A Journal of Mathematics

  • Involve
  • Volume 8, Number 3 (2015), 385-400.

Parameter identification and sensitivity analysis to a thermal diffusivity inverse problem

Brian Leventhal, Xiaojing Fu, Kathleen Fowler, and Owen Eslinger

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Abstract

The solution to inverse problems is an application shared by mathematicians, scientists, and engineers. For this work, a set of shallow soil temperatures measured at eight depths between 0 and 30 cm and sampled every five minutes over 24 hours is used to determine the diffusivity of the soil. Thermal diffusivity is a modeling parameter that impacts how heat flows through soil. In particular, it is not known in advance if the subsurface region is homogeneous or heterogeneous, which means the thermal diffusivity may or may not depend on depth. To this end, it is not clear which assumptions may apply to represent the physical system embedded within the parameter estimation problem. Analytic methods and a simulation based least-squares approach to approximate the diffusivity are compared to fit the temperature profiles to different heat flow models. The simulation is based on a spatially dependent, nonsteady-state discretization to a partial differential equation. To complete the work, a statistical sensitivity study using analysis of variance is used to understand how errors that arise in the modeling phase impact the final model. We show that for the analytic methods, errors in the initial fitting of the temperature data to sinusoidal boundary conditions can have a strong impact on the thermal diffusivity values. Our proposed framework shows that this soil sample is heterogeneous and that modeling depends significantly on data used as top and bottom boundary conditions. This work offers a protocol to determine the soil type and model sensitivities using analytic, numerical, and statistical approaches and is applicable to modifications of the classic heat equation found across disciplines.

Article information

Source
Involve, Volume 8, Number 3 (2015), 385-400.

Dates
Received: 28 April 2011
Revised: 11 November 2013
Accepted: 20 December 2013
First available in Project Euclid: 22 November 2017

Permanent link to this document
https://projecteuclid.org/euclid.involve/1511370883

Digital Object Identifier
doi:10.2140/involve.2015.8.385

Mathematical Reviews number (MathSciNet)
MR3356081

Zentralblatt MATH identifier
06445666

Subjects
Primary: 35K05: Heat equation 49N45: Inverse problems 62J10: Analysis of variance and covariance
Secondary: 35Q93: PDEs in connection with control and optimization

Keywords
inverse problems subsurface flow sensitivity analysis

Citation

Leventhal, Brian; Fu, Xiaojing; Fowler, Kathleen; Eslinger, Owen. Parameter identification and sensitivity analysis to a thermal diffusivity inverse problem. Involve 8 (2015), no. 3, 385--400. doi:10.2140/involve.2015.8.385. https://projecteuclid.org/euclid.involve/1511370883


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References

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