A Model-Based Approach for Continuous-Time Policy Evaluation with Unknown Lévy Process Dynamics

Speaker: Qihao Ye (UCSD) Dates: 2024/01/26 Location: zoom Abstract: This research presents a framework for evaluating policies in a continuous-time setting, where the dynamics are unknown and represented by Lévy processes. Initially, we estimate the model using available trajectory data,…

Exponentially Convergent Multiscale Methods Based on Edge Coupling: Example of Helmholtz Equation

Speaker: Yixuan Wang(Caltech) Dates: 2023/11/16  4-5pm Location: online, link Abstract:We provide a concise review of the exponentially convergent multiscale finite element method (ExpMsFEM) for efficient model reduction of PDEs in heterogeneous media without scale separation and in high-frequency wave propagation….

BDDC Algorithms for Advection-diffusion problems with HDG Discretizations

Speaker: Jinjin Zhang (OSU) Dates: 2023/11/09 Location: MA 105 Abstract: In this talk, I will talk about the balancing domain decomposition by constraints  (BDDC)  methods for the non-symmetric positive definite system arising from the hybridizable discontinuous Galerkin (HDG) discretization of advection-diffusion…

Realizability-Preserving DG-IMEX Method for a Two-Moment Model of Special Relativistic Transport

Speaker: Joseph Hunter (OSU) Dates: 2023/11/01 Location: MA 105 Abstract: Special relativistic transport models are important for describing the transport of neutrinos, with applications to supernovae and gravitational waves.  We study a two-moment model that evolves the Eulerian moments of…

Recent advances in discontinuous Galerkin discretization of Cahn–Hilliard–Navier–Stokes models for systems of two-phase flows

Speaker: Chen Liu (Purdue) Dates: 2023/10/26 Location: Zoom, link Abstract: Efficient and accurate pore-scale fluid dynamics simulators have important applications in digital rock physics. One of the popular approaches for modeling two-phase fluid flow in micro-to-millimeter pore structures is to…

Introduction to Nonlocal Calculus

Speaker: Zhaolong Han (UCSD) Dates: 2023/10/20 Location: Zoom, link Abstract: There has been a growing interest in the study of nonlocal models as more general and sometimes more realistic alternatives to the conventional PDE models. In this talk, we will…

Optimal Error Estimates of Ultra-weak Discontinuous Galerkin Methods with Generalized Numerical Fluxes

Speaker: Yuan Chen (OSU) Dates: 2023/10/06 Location: MW154 Abstract: We study ultra-weak discontinuous Galerkin methods with generalized numerical fluxes for multi-dimensional high order partial differential equations on both unstructured simplex and Cartesian meshes. The equations we consider as examples are…

Combining Stochastic Parameterized Reduced-Order Models with Machine Learning for Data Assimilation and Uncertainty Quantification with Partial Observations

Speaker: Changhong Mou (UWM) Dates: 2023/09/29 Time: 4:10-5:10 (EST) Location: Zoom, link Abstract: A hybrid data assimilation algorithm is developed for complex dynamical systems with partial observations. The method starts with applying a spectral decomposition to the entire spatiotemporal fields,…

The semi-implicit DLN algorithm for the Navier-Stokes equations

Speaker: Wenlong Pei (OSU) Dates: 2023/09/21 Location: MW105 Abstract:Dahlquist, Liniger, and Nevanlinna design a family of one-leg, two-step methods (the DLN method) that is second order,A−andG−stable for arbitrary, non-uniform time steps. Recently, the implementation of the DLN method can be simplified…

Efficient ensemble methods for simulating groundwater-surface flows

Speaker: Ying Li (OSU) Dates: 2023/09/15 Location: MW154 Abstract: We propose and analyze a series of efficient, unconditionally stable, ensemble methods for stimulating groundwater-surface flows governed by the Stokes-Darcy model. For systems like the surface-groundwater flows, predictive simulations must account…