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 Arts and Sciences DESCRIPTION:Abstract:High-order numerical simulations of hyperbolic conserv ation laws frequently lack inherent mechanisms to preserve physical positi vity, leading to computational failures near strong shocks or near-vacuum states. To address this, we introduce a conservative sweeping framework de signed to enforce positivity of density and pressure as a standalone post- processing procedure. The approach generalizes a scalar mass-redistributio n technique using the Zhang-Shu scaling limiter as a projection strategy t o treat nonlinear pressure in the Euler equations. Because the positivity- preserving mechanism operates independently from the spatial discretizatio n, it provides highly modular and non-intrusive stabilization for existing solvers.We first demonstrate the framework's robust performance in explic it fifth-order finite difference WENO schemes for extreme compressible Eul er flows such as high-Mach jets and strong blast waves. Crucially, as a po st-processing step, this framework easily extends to implicit time-steppin g schemes, where guaranteeing positivity and conservation traditionally pr esents a significant algorithmic hurdle. We present results highlighting i ts ability to successfully correct large positivity violations in fully im plicit continuous Galerkin applications. The general framework is applicab le to finite volume and discontinuous Galerkin discretizations, and may be used to treat any concave function of the conserved variables. Thus, it i s an ideal candidate for internal energy treatment in Navier-Stokes and MH D simulations.\nEvent page: https://www.umassd.edu/events/cms/10-28-26-chl oe-griffin-brown-non-intrusive-positivity-preservation.php\nEvent link: ht tps://www.cscdr.umassd.edu/seminars X-ALT-DESC;FMTTYPE=text/html:

Abstr act:

High-order numerical simula tions of hyperbolic conservation laws frequently lack inherent mechanisms to preserve physical positivity\, leading to computational failures near s trong shocks or near-vacuum states. To address this\, we introduce a conse rvative sweeping framework designed to enforce positivity of density and p ressure as a standalone post-processing procedure. The approach generalize s a scalar mass-redistribution technique using the Zhang-Shu scaling limit er as a projection strategy to treat nonlinear pressure in the Euler equat ions. Because the positivity-preserving mechanism operates independently f rom the spatial discretization\, it provides highly modular and non-intrus ive stabilization for existing solvers.

We first demonstrate the framework's robust performance in explici t fifth-order finite difference WENO schemes for extreme compressible Eule r flows such as high-Mach jets and strong blast waves. Crucially\, as a po st-processing step\, this framework easily extends to implicit time-steppi ng schemes\, where guaranteeing positivity and conservation traditionally presents a significant algorithmic hurdle. We present results highlighting its ability to successfully correct large positivity violations in fully implicit continuous Galerkin applications. The general framework is applic able to finite volume and discontinuous Galerkin discretizations\, and may be used to treat any concave function of the conserved variables. Thus\, it is an ideal candidate for internal energy treatment in Navier-Stokes an d MHD simulations.

Event page: https://www.umassd.edu/events/cms/10-28-26-chloe-griffin-brown- non-intrusive-positivity-preservation.php
Event link: https://www.cscdr.umassd.edu/seminars

DTSTAMP:20261016T155916 DTSTART;TZID=America/New_York:20261028T130000 DTEND;TZID=America/New_York:20261028T140000 LOCATION:Online SUMMARY;LANGUAGE=en-us:Non-Intrusive Positivity Preservation: A Conservativ e Sweeping Framework for High-Order Discretizations of Hyperbolic Systems UID:0efb7f4ce48ecc96dd92ad3e107d4353@www.umassd.edu END:VEVENT END:VCALENDAR