BEGIN:VCALENDAR VERSION:2.0 X-WR-CALNAME:EventsCalendar PRODID:-//hacksw/handcal//NONSGML v1.0//EN CALSCALE:GREGORIAN BEGIN:VTIMEZONE TZID:America/New_York LAST-MODIFIED:20240422T053451Z TZURL:https://www.tzurl.org/zoneinfo-outlook/America/New_York X-LIC-LOCATION:America/New_York BEGIN:DAYLIGHT TZNAME:EDT TZOFFSETFROM:-0500 TZOFFSETTO:-0400 DTSTART:19700308T020000 RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU END:DAYLIGHT BEGIN:STANDARD TZNAME:EST TZOFFSETFROM:-0400 TZOFFSETTO:-0500 DTSTART:19701101T020000 RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU END:STANDARD END:VTIMEZONE BEGIN:VEVENT CATEGORIES:College of Engineering,Graduate Studies,Lectures and Seminars,Th esis/Dissertations DESCRIPTION:Abstract: Self-gravity plays a crucial role in the a strophysics of type Ia supernovae (SNe Ia). Understanding the extreme phys ics of these events demands accurate hydrodynamical simulations enabled by multiphysics frameworks such as FLASH. In these simulations, direct pairw ise gravitational interactions scale as N2, which can quickly become expan sive for large scale simulations. To reduce the computational cost, FLASH employs approximation methods, including fast multipole and BHTree solvers , where the computational cost scales linearly with the system. Within thi s framework, FLASH uses an operator-split approach to couple separately ev olved hydrodynamics and gravity at each timestep. My thesis focuses on the BHTree solver and quantifies its suitability for SNe Ia applications thro ugh targeted verification and performance studies. I evaluate force accura cy and conservation behaviour across test problems, and compare BHTree aga inst other gravity solvers to characterize the relevant accuracy-cost trad eoff for production simulations. The resulting methodology is intended to guide solver selection and simulation setup for large self-gravitating cal culations, and to support the broader goal of reliable, scalable computati onal tools for stellar explosions and related astrophysical fluid systems. Advisor: Dr. Robert Fisher, Department of Physics, (Robert.fisher@umassd. edu) Committee members: Dr. Renuka Rajapakse, Department of PhysicsD r. Janyi Wang, Department of Physics Note: All PHY Graduate Students a re encouraged to attend.\nEvent page: https://www.umassd.edu/events/cms/tr ee-based-gravity-solver-for-3d-hydrodynamical-simulations-of-binary-white- dwarfs-merger-type-ia-supernovae.php X-ALT-DESC;FMTTYPE=text/html:

Abstract:

Se lf-gravity plays a crucial role in the astrophysics of type Ia supernovae (SNe Ia). Understanding the extreme physics of these events demands accura te hydrodynamical simulations enabled by multiphysics frameworks such as F LASH. In these simulations\, direct pairwise gravitational interactions sc ale as N2\, which can quickly become expansive for large scale simulations . To reduce the computational cost\, FLASH employs approximation methods\, including fast multipole and BHTree solvers\, where the computational cos t scales linearly with the system. Within this framework\, FLASH uses an o perator-split approach to couple separately evolved hydrodynamics and grav ity at each timestep.

My thesis focuses on the BHTree solver and q uantifies its suitability for SNe Ia applications through targeted verific ation and performance studies. I evaluate force accuracy and conservation behaviour across test problems\, and compare BHTree against other gravity solvers to characterize the relevant accuracy-cost tradeoff for production simulations. The resulting methodology is intended to guide solver select ion and simulation setup for large self-gravitating calculations\, and to support the broader goal of reliable\, scalable computational tools for st ellar explosions and related astrophysical fluid systems.

Advisor:
Dr. Robert Fisher\, Department of Physics\, (Robert.fisher@umassd.e du)

Committee members:
Dr. Renuka Rajapakse\, Departme nt of Physics
Dr. Janyi Wang\, Department of Physics

Note: All PHY Graduate Students are encouraged to attend.

Event page: https://www.umassd.edu/events/cms/tree-based-gravity-solver-for-3d- hydrodynamical-simulations-of-binary-white-dwarfs-merger-type-ia-supernova e.php

DTSTAMP:20260418T055503 DTSTART;TZID=America/New_York:20260507T104500 DTEND;TZID=America/New_York:20260507T114500 LOCATION:SENG 201 SUMMARY;LANGUAGE=en-us:Tree based gravity solver for 3D hydrodynamical simu lations of binary white dwarfs merger type Ia supernovae UID:b049684919951b8a9fc3c2c49b34363f@www.umassd.edu END:VEVENT END:VCALENDAR