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Articles 1 - 9 of 9
Full-Text Articles in Physical Processes
Simulating The Eccentricity Evolution Of Accreting Equal-Mass Binaries: Numerical Sensitivity To The Computational Domain Size And Grid Resolution, Zhongtian Hu
All Theses
With high resolution hydrodynamics simulations, we show that the optimal values of domain radius and grid resolution for the software Sailfish when simulating time-based eccentricity evolution of equal mass, non-circular accreting binaries in a circumbinary disk to be $r_{\rm out} \leq 15a$ and $\delta x / a \le 0.01 $. These values provide a useful guideline for optimizing the performance of simulation runs while maintaining scientific accuracy. Each artificial parameter is probed with 15 runs of 2000 orbits each.
A New Galactic Wind Model For Cosmological Simulations, Shuiyao Huang
A New Galactic Wind Model For Cosmological Simulations, Shuiyao Huang
Doctoral Dissertations
The propagation and evolution of cold galactic winds in galactic haloes is crucial to galaxy formation models. However, modelling of this process in hydrodynamic simulations of galaxy formation is over-simplified owing to a lack of numerical resolution and often neglects critical physical processes such as hydrodynamic instabilities and thermal conduction. In this thesis, I propose an analytic model, Physically Evolved Winds (PhEW), that calculates the evolution of individual clouds moving supersonically through a uniform ambient medium. The model reproduces predictions from very high resolution cloud-crushing simulations that include isotropic thermal conduction over a wide range of physical conditions. I also …
The Effects Of Disc Self-Gravity And Radiative Cooling On The Formation Of Gaps And Spirals By Young Planets, Shangjia Zhang, Zhaohuan Zhu
The Effects Of Disc Self-Gravity And Radiative Cooling On The Formation Of Gaps And Spirals By Young Planets, Shangjia Zhang, Zhaohuan Zhu
Physics & Astronomy Faculty Research
We have carried out 2D hydrodynamical simulations to study the effects of disc self-gravity and radiative cooling on the formation of gaps and spirals. (1) With disc self-gravity included, we find stronger, more tightly wound spirals and deeper gaps in more massive discs. The deeper gaps are due to the larger Angular Momentum Flux (AMF) of the waves excited in more massive discs, as expected from the linear theory. The position of the secondary gap does not change, provided that the disc is not extremely massive (Q ≳ 2). (2) With radiative cooling included, the excited spirals become monotonically more …
Morphological Signatures Induced By Dust Back Reactions In Discs With An Embedded Planet, Chao-Chin Yang, Zhaohuan Zhu
Morphological Signatures Induced By Dust Back Reactions In Discs With An Embedded Planet, Chao-Chin Yang, Zhaohuan Zhu
Physics & Astronomy Faculty Research
Recent observations have revealed a gallery of substructures in the dust component of nearby protoplanetary discs, including rings, gaps, spiral arms, and lopsided concentrations. One interpretation of these substructures is the existence of embedded planets. Not until recently, however, most of the modelling effort to interpret these observations ignored the dust back reaction to the gas. In this work, we conduct local-shearing-sheet simulations for an isothermal, inviscid, non-self-gravitating, razor-thin dusty disc with a planet on a fixed circular orbit. We systematically examine the parameter space spanned by planet mass (0.1Mth ≤ Mp ≤ 1Mth, where Mth is the thermal mass), …
Circumbinary Disk Inner Radius As A Diagnostic For Disk–Binary Misalignment, Alessia Franchini, Stephen H. Lubow, Rebecca G. Martin
Circumbinary Disk Inner Radius As A Diagnostic For Disk–Binary Misalignment, Alessia Franchini, Stephen H. Lubow, Rebecca G. Martin
Physics & Astronomy Faculty Research
We investigate the misalignment of the circumbinary disk around the binary HD 98800 BaBb with eccentricity e sime 0.8. Kennedy et al. observed the disk to be either at an inclination of 48° or polar aligned to the binary orbital plane. Their simulations showed that alignment from 48° to a polar configuration can take place on a shorter timescale than the age of this system. We perform hydrodynamical numerical simulations in order to estimate the cavity size carved by the eccentric binary for different disk inclinations as an independent check of polar alignment. Resonance theory suggests that torques on the …
Alignment Of A Circumbinary Disc Around An Eccentric Binary With Application To Kh 15d, Jeremy L. Smallwood, Stephen H. Lubow, Alessia Franchini, Rebecca G. Martin
Alignment Of A Circumbinary Disc Around An Eccentric Binary With Application To Kh 15d, Jeremy L. Smallwood, Stephen H. Lubow, Alessia Franchini, Rebecca G. Martin
Physics & Astronomy Faculty Research
We analyse the evolution of a mildly inclined circumbinary disc that orbits an eccentric orbit binary by means of smoothed particle hydrodynamics (SPH) simulations and linear theory. We show that the alignment process of an initially misaligned circumbinary disc around an eccentric orbit binary is significantly different than around a circular orbit binary and involves tilt oscillations. The more eccentric the binary, the larger the tilt oscillations and the longer it takes to damp these oscillations. A circumbinary disc that is only mildly inclined may increase its inclination by a factor of a few before it moves towards alignment. The …
Dust Traps In The Protoplanetary Disk Mwc 758: Two Vortices Produced By Two Giant Planets?, Clement Baruteau, Marcelo Barraza, Sebastian Perez, Simon Casassus, Ruobing Dong, Wladimir Lyra, Sebastian Marino, Valentin Christiaens, Zhaohuan Zhu, Andres Carmona, Florian Debras, Felipe Alarcon
Dust Traps In The Protoplanetary Disk Mwc 758: Two Vortices Produced By Two Giant Planets?, Clement Baruteau, Marcelo Barraza, Sebastian Perez, Simon Casassus, Ruobing Dong, Wladimir Lyra, Sebastian Marino, Valentin Christiaens, Zhaohuan Zhu, Andres Carmona, Florian Debras, Felipe Alarcon
Physics & Astronomy Faculty Research
Resolved ALMA and VLA observations indicate the existence of two dust traps in the protoplanetary disc MWC 758. By means of two-dimensional gas+dust hydrodynamical simulations post-processed with three-dimensional dust radiative transfer calculations, we show that the spirals in scattered light, the eccentric, asymmetric ring and the crescent-shaped structure in the (sub)millimetre can all be caused by two giant planets: a 1.5-Jupiter mass planet at 35 au (inside the spirals) and a 5-Jupiter mass planet at 140 au (outside the spirals). The outer planet forms a dust-trapping vortex at the inner edge of its gap (at ∼85 au), and the continuum …
Quantization In Astrophysics, Brownian Motion, And Supersymmetry, Florentin Smarandache, Victor Christianto
Quantization In Astrophysics, Brownian Motion, And Supersymmetry, Florentin Smarandache, Victor Christianto
Branch Mathematics and Statistics Faculty and Staff Publications
The present book discusses, among other things, various quantization phenomena found in Astrophysics and some related issues including Brownian Motion. With recent discoveries of exoplanets in our galaxy and beyond, this Astrophysics quantization issue has attracted numerous discussions in the past few years. Most chapters in this book come from published papers in various peer-reviewed journals, and they cover different methods to describe quantization, including Weyl geometry, Supersymmetry, generalized Schrödinger, and Cartan torsion method. In some chapters Navier-Stokes equations are also discussed, because it is likely that this theory will remain relevant in Astrophysics and Cosmology While much of the …
Transonic Inviscid Disc Flows In The Schwarzschild Metric – I, Menas Kafatos, Ruixin Yang
Transonic Inviscid Disc Flows In The Schwarzschild Metric – I, Menas Kafatos, Ruixin Yang
Mathematics, Physics, and Computer Science Faculty Articles and Research
The coupled hydrodynamic equations governing equatorial flows applicable to inviscid disc accretion in the Schwarzschild metric are solved analytically and numerically. Here, we concentrate on the transonic solutions, that represent physically allowed accretion on to black holes. A polytropic equation linking gas pressure and density is assumed, and solutions are obtained for different conditions, such as isothermal and adiabatic gas flows. The dependence of those solutions on the angular momentum is explored. Under certain conditions, when there exist multiple possible sonic points, the numerical simulation automatically zeros in to the unique transonic solution passing through one of the sonic points.