Solving the PDE for a Sphere in Vacuum: Temperature over Time

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SUMMARY

The discussion centers on solving the partial differential equation (PDE) for temperature as a function of time for a sphere in a vacuum, specifically addressing the scenario of a moon in space. The boundary condition is identified as a nonlinear function of temperature raised to the fourth power, reflecting radiative heat loss. Participants suggest that numerical methods may simplify the problem, and reference is made to the heat equation as a foundational concept. Assumptions regarding energy input and surface heat capacity are crucial for accurate modeling.

PREREQUISITES
  • Understanding of partial differential equations (PDEs)
  • Familiarity with the heat equation
  • Knowledge of radiative heat transfer principles
  • Basic numerical methods for solving differential equations
NEXT STEPS
  • Study the heat equation in detail, focusing on its application to spherical coordinates
  • Explore numerical methods for solving PDEs, such as finite difference or finite element methods
  • Research the Stefan-Boltzmann law and its implications for radiative heat transfer
  • Investigate the effects of varying heat capacities in different materials on temperature modeling
USEFUL FOR

This discussion is beneficial for physicists, engineers, and researchers interested in thermal dynamics, particularly those working on modeling temperature changes in celestial bodies or similar systems in vacuum environments.

MarkL
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Is there a PDE describing temperature as a function of time for a sphere in a vacuum (a moon in space)?

Since it can only radiate, the boundary would be a function of temperature to the fourth power (nonlinear), right?

Is there a book or thread out there I can reference?

Maybe this can be handled easily numerically.

Thank you

Mark
 
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MarkL said:
Is there a PDE describing temperature as a function of time for a sphere in a vacuum (a moon in space)?

Since it can only radiate, the boundary would be a function of temperature to the fourth power (nonlinear), right?

Is there a book or thread out there I can reference?

Maybe this can be handled easily numerically.

Thank you

Mark

You will need some assumptions about the energy coming in, and about the heat capacity of the surface. The latter tells you how quickly temperature drops as energy is radiated. It can be more complicated if the planet is water covered, or otherwise has some heat capacity below the surface.

Cheers -- sylas
 
Apply the http://en.wikipedia.org/wiki/Heat_equation" . Due to the symmetry of a sphere it can be done as a one dimensional problem with the radius of the sphere as the variable.
 
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