• Data-driven recovery of hidden hysics in reduced order modeling of fluid flows 

      Pawar, Suraj; Ahmed, Shady E; San, Omer; Rasheed, Adil (Peer reviewed; Journal article, 2020)
      In this article, we introduce a modular hybrid analysis and modeling (HAM) approach to account for hidden physics in reduced order modeling (ROM) of parameterized systems relevant to fluid dynamics. The hybrid ROM framework ...
    • Data-driven recovery of hidden physics in reduced order modeling of fluid flows 

      Pawar, Suraj; Ahmed, Shady E; San, Omer; Rasheed, Adil (Peer reviewed; Journal article, 2020)
      In this article, we introduce a modular hybrid analysis and modeling (HAM) approach to account for hidden physics in reduced order modeling (ROM) of parameterized systems relevant to fluid dynamics. The hybrid ROM framework ...
    • An evolve-then-correct reduced order model for hidden fluid dynamics 

      Pawar, Suraj; Ahmed, Shady E; San, Omer; Rasheed, Adil (Journal article; Peer reviewed, 2020)
      n this paper, we put forth an evolve-then-correct reduced order modeling approach that combines intrusive and nonintrusive models to take hidden physical processes into account. Specifically, we split the underlying dynamics ...
    • Forward sensitivity approach for estimating eddy viscosity closures in nonlinear model reduction 

      Ahmed, Shady E; Bhar, Kinjal; San, Omer; Rasheed, Adil (Peer reviewed; Journal article, 2020)
      In this paper, we propose a variational approach to estimate eddy viscosity using forward sensitivity method (FSM) for closure modeling in nonlinear reduced order models. FSM is a data assimilation technique that blends ...
    • Hybrid analysis and modeling for next generation of digital twins 

      Pawar, Suraj; Ahmed, Shady E; San, Omer; Rasheed, Adil (Peer reviewed; Journal article, 2021)
      The physics-based modeling has been the workhorse for many decades in many scientific and engineering applications ranging from wind power, weather forecasting, and aircraft design. Recently, data-driven models are ...
    • Interface learning of multiphysics and multiscale systems 

      Ahmed, Shady E; San, Omer; Kara, Kursat; Younis, Rami; Rasheed, Adil (Peer reviewed; Journal article, 2020)
      Complex natural or engineered systems comprise multiple characteristic scales, multiple spatiotemporal domains, and even multiple physical closure laws. To address such challenges, we introduce an interface learning paradigm ...
    • A long short term memory for hybrid uplifted reduced order models. 

      Ahmed, Shady E; San, Omer; Rasheed, Adil; Trian, Iliescu (Peer reviewed; Journal article, 2020)
      In this paper, we introduce an uplifted reduced order modeling (UROM) approach through the integration of standard projection based methods with long short-term memory (LSTM) embedding. Our approach has three modeling ...
    • Long short-term memory embedded nudging schemes for nonlinear data assimilation of geophysical flows 

      Pawar, Suraj; Ahmed, Shady E; San, Omer; Rasheed, Adil; Navon, Ionel M (Peer reviewed; Journal article, 2020)
      Reduced rank nonlinear filters are increasingly utilized in data assimilation of geophysical flows but often require a set of ensemble forward simulations to estimate forecast covariance. On the other hand, predictor–corrector ...
    • Memory embedded non-intrusive reduced order modeling of non-ergodic flows 

      Ahmed, Shady E; Rahman, Sk. Mashfiqur; San, Omer; Rasheed, Adil; Navon, Ionel M (Journal article; Peer reviewed, 2019)
      Generating a digital twin of any complex system requires modeling and computational approaches that are efficient, accurate, and modular. Traditional reduced order modeling techniques are targeted at only the first two, ...
    • Multifidelity computing for coupling full and reduced order models 

      Ahmed, Shady E; San, Omer; Kara, Kursat; Younis, Rami; Rasheed, Adil (Peer reviewed; Journal article, 2021)
      Hybrid physics-machine learning models are increasingly being used in simulations of transport processes. Many complex multiphysics systems relevant to scientific and engineering applications include multiple spatiotemporal ...
    • Nonlinear proper orthogonal decomposition for convection-dominated flows 

      Ahmed, Shady E; San, Omer; Rasheed, Adil; Trian, Iliescu (Peer reviewed; Journal article, 2021)
      Autoencoder techniques find increasingly common use in reduced order modeling as a means to create a latent space. This reduced order representation offers a modular data-driven modeling approach for nonlinear dynamical ...
    • A nudged hybrid analysis and modeling approach for realtime wake-vortex transport and decay prediction 

      Ahmed, Shady E; Pawar, Suraj; San, Omer; Rasheed, Adil; Tabib, Mandar (Journal article, 2020)
      We put forth a long short-term memory (LSTM) nudging framework for the enhancement of reduced order models (ROMs) of fluid flows utilizing noisy measurements for air traffic improvements. Toward emerging applications of ...
    • On closures for reduced order models— A spectrum of first-principle to machine-learned avenues 

      Ahmed, Shady E; Pawar, Suraj; San, Omer; Rasheed, Adil; Trian, Iliescu; Noack, Bernd R. (Peer reviewed; Journal article, 2021)
      For over a century, reduced order models (ROMs) have been a fundamental discipline of theoretical fluid mechanics. Early examples include Galerkin models inspired by the Orr–Sommerfeld stability equation and numerous vortex ...
    • Reduced order modeling of fluid flows: Machine learning, Kolmogorov barrier, closure modeling, and partitioning 

      Ahmed, Shady E; Pawar, Suraj; San, Omer; Rasheed, Adil (Peer reviewed; Journal article, 2020)
      In this paper, we put forth a long short-term memory (LSTM) nudging framework for the enhancement of reduced order models (ROMs) of fluid flows utilizing noisy measurements. We build on the fact that in a realistic ...