Exploring Convection in the Vicinity of Localized Decreases in Thermal Diffusivity

Session Number

PHYS 32

Advisor(s)

Liam O’Connor, Northwestern University, Center for Interdisciplinary Research in Astrophysics

Discipline

Physical Science

Start Date

17-4-2024 10:25 AM

End Date

17-4-2024 10:40 AM

Abstract

Context: Computational convection simulations are a critical tool for understanding the dynamics of a variety of different environments; including the complex interiors of stars. Methods Direct-Numerical-Simulations of Rayleigh-Bernard convection are performed within a periodic rectangular domain. A localized decrease in thermal diffusivity (𝛼𝛼) is imparted within the domain at a certain temperature, with a parameterized amplitude (A) of decrease. Runs are performed at a constant Prandtl number (Pr = 1), and aspect ratio (Ⲅ = 4). Simulations are run within a comprehensive set of amplitudes between A = 0.3 and A = 0.9, and at Rayleigh numbers between Ra = 10 6 and Ra = 10 7 . The vertical heat fluxes of the system, along with globally- averaged Reynolds and Nusselt numbers are also collected as a measure of turbulence and convective efficiency.

Results: The convective heat flux showed significant differences between the nominal (A = 0) and decreased cases (0

Discussion: The lack of significant change in for the majority of amplitudes indicates a conservation of convective efficiency in the vicinity of decreases in thermal diffusivity. The work gathered here has far reaching implications on astrophysical systems such as variable stars.

Results The convective heat flux showed significant differences between the nominal (A = 0) and decreased cases (07.

Discussion The lack of significant change in for the majority of amplitudes indicates a conservation of convective efficiency in the vicinity of decreases in thermal diffusivity. The work gathered here has far-reaching implications on astrophysical systems such as variable stars.

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Apr 17th, 10:25 AM Apr 17th, 10:40 AM

Exploring Convection in the Vicinity of Localized Decreases in Thermal Diffusivity

Context: Computational convection simulations are a critical tool for understanding the dynamics of a variety of different environments; including the complex interiors of stars. Methods Direct-Numerical-Simulations of Rayleigh-Bernard convection are performed within a periodic rectangular domain. A localized decrease in thermal diffusivity (𝛼𝛼) is imparted within the domain at a certain temperature, with a parameterized amplitude (A) of decrease. Runs are performed at a constant Prandtl number (Pr = 1), and aspect ratio (Ⲅ = 4). Simulations are run within a comprehensive set of amplitudes between A = 0.3 and A = 0.9, and at Rayleigh numbers between Ra = 10 6 and Ra = 10 7 . The vertical heat fluxes of the system, along with globally- averaged Reynolds and Nusselt numbers are also collected as a measure of turbulence and convective efficiency.

Results: The convective heat flux showed significant differences between the nominal (A = 0) and decreased cases (0

Discussion: The lack of significant change in for the majority of amplitudes indicates a conservation of convective efficiency in the vicinity of decreases in thermal diffusivity. The work gathered here has far reaching implications on astrophysical systems such as variable stars.

Results The convective heat flux showed significant differences between the nominal (A = 0) and decreased cases (07.

Discussion The lack of significant change in for the majority of amplitudes indicates a conservation of convective efficiency in the vicinity of decreases in thermal diffusivity. The work gathered here has far-reaching implications on astrophysical systems such as variable stars.