서브메뉴
검색
Fluid Instabilities in Stellar Interiors: Fundamental Properties and Transport Processes
Fluid Instabilities in Stellar Interiors: Fundamental Properties and Transport Processes
상세정보
- 자료유형
- 학위논문 서양
- 최종처리일시
- 20260202103126
- ISBN
- 9798314898918
- DDC
- 523
- 서명/저자
- Fluid Instabilities in Stellar Interiors: Fundamental Properties and Transport Processes
- 발행사항
- [Sl] : University of Colorado at Boulder, 2025
- 발행사항
- Ann Arbor : ProQuest Dissertations & Theses, 2025
- 형태사항
- 120 p
- 주기사항
- Source: Dissertations Abstracts International, Volume: 86-11, Section: B.
- 주기사항
- Advisor: Brown, Benjamin.
- 학위논문주기
- Thesis (Ph.D.)--University of Colorado at Boulder, 2025.
- 초록/해제
- 요약Fluid dynamical instabilities play a crucial role in the transport of heat in stellar interiors, and drive a wide variety of interesting phenomena. The highly turbulent and nonlinear nature of these instabilities, coupled with the need to resolve a challenging range of spatial and temporal scales, makes their behaviour difficult to predict and model. A long-standing problem in stellar modelling is parameterising transport and mixing processes in turbulent regions. This thesis presents a series of idealised numerical experiments exploring transport processes of fluid instabilities in stars.The first of these experiments studies magnetohydrodynamic Rayleigh-Benard convection (RBC), directly measuring force balances between the Lorentz, buoyancy, and inertial forces in order to quantify magnetic constraint. From these simulations we find three simulation regimes: a "constrained'' regime where the background magnetic field dominates, a "magnetically influenced'' regime where nonlinear Lorentz and inertial forces balance, and a transitional regime between the two. We have learned about a constrained yet turbulent regime for large external magnetic fields, where the traditional hydrodynamic scaling of the heat flux is recovered, despite inherently nonlinear effects from the Lorentz force.The next of these studies focuses on simulations of thermohaline convective fronts in polluted white dwarfs (WDs). Current models of polluted white dwarfs often do not account for this effect, which can increase the inferred accretion rate by orders of magnitude when it is included. We find the turbulent flux of metals broadly dominates over the diffusive flux in a manner consistent with existing mixing prescriptions implemented in some stellar evolution models. Thus, our results broadly support polluted WD models that include thermohaline mixing in their estimates of the settling rate.In the final study we focus on ``parasitic" shear instabilities that saturate the thermohaline instability. Whilst most astrophysical flows have extremely high Reynolds and magnetic Reynolds numbers, these parasitic instabilities occur on small scales, where the effects of viscosity and resistivity are more significant. We find that linear stability analysis fails to predict the dynamical differences between low magnetic Reynolds number (Rm) flows and their higher Rm counterparts. we show that including viscosity and resistivity introduces two new modes of instability, one of which exists for any nonzero magnetic field strength as long as the magnetic Prandtl number, Pm 1, and demonstrate numerically that this mode saturates in a quasi-stationary state dominated by counter-propagating solitons.
- 일반주제명
- Astrophysics
- 일반주제명
- Electromagnetics
- 일반주제명
- Fluid mechanics
- 키워드
- Convection
- 키워드
- Reynolds number
- 기타저자
- University of Colorado at Boulder Astrophysical and Planetary Sciences
- 기본자료저록
- Dissertations Abstracts International. 86-11B.
- 전자적 위치 및 접속
- 로그인 후 원문을 볼 수 있습니다.
MARC
008260126s2025 us c eng d■001000017357071
■00520260202103126
■006m o d
■007cr#unu||||||||
■020 ▼a9798314898918
■035 ▼a(MiAaPQ)AAI31938835
■040 ▼aMiAaPQ▼cMiAaPQ
■0820 ▼a523
■1001 ▼aCresswell, Imogen.▼0(orcid)0000-0002-4538-7320
■24510▼aFluid Instabilities in Stellar Interiors: Fundamental Properties and Transport Processes
■260 ▼a[Sl]▼bUniversity of Colorado at Boulder▼c2025
■260 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2025
■300 ▼a120 p
■500 ▼aSource: Dissertations Abstracts International, Volume: 86-11, Section: B.
■500 ▼aAdvisor: Brown, Benjamin.
■5021 ▼aThesis (Ph.D.)--University of Colorado at Boulder, 2025.
■520 ▼aFluid dynamical instabilities play a crucial role in the transport of heat in stellar interiors, and drive a wide variety of interesting phenomena. The highly turbulent and nonlinear nature of these instabilities, coupled with the need to resolve a challenging range of spatial and temporal scales, makes their behaviour difficult to predict and model. A long-standing problem in stellar modelling is parameterising transport and mixing processes in turbulent regions. This thesis presents a series of idealised numerical experiments exploring transport processes of fluid instabilities in stars.The first of these experiments studies magnetohydrodynamic Rayleigh-Benard convection (RBC), directly measuring force balances between the Lorentz, buoyancy, and inertial forces in order to quantify magnetic constraint. From these simulations we find three simulation regimes: a "constrained'' regime where the background magnetic field dominates, a "magnetically influenced'' regime where nonlinear Lorentz and inertial forces balance, and a transitional regime between the two. We have learned about a constrained yet turbulent regime for large external magnetic fields, where the traditional hydrodynamic scaling of the heat flux is recovered, despite inherently nonlinear effects from the Lorentz force.The next of these studies focuses on simulations of thermohaline convective fronts in polluted white dwarfs (WDs). Current models of polluted white dwarfs often do not account for this effect, which can increase the inferred accretion rate by orders of magnitude when it is included. We find the turbulent flux of metals broadly dominates over the diffusive flux in a manner consistent with existing mixing prescriptions implemented in some stellar evolution models. Thus, our results broadly support polluted WD models that include thermohaline mixing in their estimates of the settling rate.In the final study we focus on ``parasitic" shear instabilities that saturate the thermohaline instability. Whilst most astrophysical flows have extremely high Reynolds and magnetic Reynolds numbers, these parasitic instabilities occur on small scales, where the effects of viscosity and resistivity are more significant. We find that linear stability analysis fails to predict the dynamical differences between low magnetic Reynolds number (Rm) flows and their higher Rm counterparts. we show that including viscosity and resistivity introduces two new modes of instability, one of which exists for any nonzero magnetic field strength as long as the magnetic Prandtl number, Pm 1, and demonstrate numerically that this mode saturates in a quasi-stationary state dominated by counter-propagating solitons.
■590 ▼aSchool code: 0051.
■650 4▼aAstrophysics
■650 4▼aElectromagnetics
■650 4▼aFluid mechanics
■653 ▼aAstrophysical fluids
■653 ▼aConvection
■653 ▼aStellar interiors
■653 ▼aTurbulent processes
■653 ▼aReynolds number
■690 ▼a0596
■690 ▼a0607
■690 ▼a0204
■71020▼aUniversity of Colorado at Boulder▼bAstrophysical and Planetary Sciences.
■7730 ▼tDissertations Abstracts International▼g86-11B.
■790 ▼a0051
■791 ▼aPh.D.
■792 ▼a2025
■793 ▼aEnglish
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17357071▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
