Browsing Rensselaer Libraries by Author "Sahni, Onkar"
Now showing items 1-20 of 86
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A high-order and efficient numerical algorithm for conjugate heat transfer problems
Meng, Fanlong (Rensselaer Polytechnic Institute, Troy, NY, 2018-08)To improve numerical schemes associated with CHT problem, we first restrict our consideration to CHT problems involving only heat transfer, as for example in solids. Then we describe a new partitioned approach for solving ... -
A mesh resolution study for large eddy simulation of flow interactions of a finite-span synthetic jet on an airfoil
Larrabee, Erik (Rensselaer Polytechnic Institute, Troy, NY, 2018-12)The primary objective of this study is to investigate the effect of mesh resolution on the accuracy of large eddy simulation (LES) based prediction of complex flow interactions that arise between a finite-span synthetic ... -
A modular matrix-free approach to multidisciplinary design optimization
Dener, Alp (Rensselaer Polytechnic Institute, Troy, NY, 2017-12)In this thesis, we propose a reduced-space inexact-Newton-Krylov (RSNK) algorithm that can address the challenges posed by the IDF formulation. RSNK achieves this with three key components: a matrix-free formulation that ... -
A parallel and adaptive interface tracking approach for evolving geometry problems
Yang, Fan (Rensselaer Polytechnic Institute, Troy, NY, 2019-12)Numerical simulations employing an interface tracking approach are desired in many evolving-geometry applications, particularly those involving fluid-structure and/or multiphase interactions with moving boundaries/interfaces. ... -
A stabilized finite element method for compressible phase change phenomena
Zhang, Yu (Rensselaer Polytechnic Institute, Troy, NY, 2020-05)This thesis presents a finite element based method that addresses these challenges. The discretization is continuous everywhere except at the interface, and it inherits its stability properties from both continuous and ... -
A study of the flow physics on a swept wing and the application of steady blowing to separation control
Parks, John (Rensselaer Polytechnic Institute, Troy, NY, 2022-08)An experimental study was conducted to understand the effect of steady blowing from segmented jets along the leading edge of a 30° swept wing with an aspect ratio of approximately 4, with a twist of approximately −2.5° ... -
Adaptive construction of locally anisotropic spectral discretization for stochastic PDEs
Lapierre, Joseph (Rensselaer Polytechnic Institute, Troy, NY, 2018-05)Many stochastic problems are anisotropic in nature in that at certain spatial locations the solution may depend only on a couple of random variables and have negligible dependence on others. This anisotropic nature of ... -
Adaptive large eddy simulation for complex unsteady flows
Rane, Jitesh, Dilipkumar (Rensselaer Polytechnic Institute, Troy, NY, 2023-05)Large eddy simulation (LES) is an attractive turbulence modeling approach due to thebalance it provides between computational cost and turbulence/scale-resolving capabilities. LES is shown to be robust and provides accurate ... -
Advances in computational fluid dynamics with discrete entropy properties : stability, unstructured grids, and adaptivity
Crean, Jared (Rensselaer Polytechnic Institute, Troy, NY, 2019-12)The main theme of this work is the development and application of entropy-stable discretizations. These discretizations inherit a nonlinear stability property from the continuous equations and they show great promise toward ... -
Aerodynamic shape optimization of unsteady, chaotic flows
Ashley, Anthony (Rensselaer Polytechnic Institute, Troy, NY, 2019-08)First, a novel ensemble Newton-Krylov method is presented, which successfully improves upon a chosen objective function for the chaotic Lorenz '63 system. Next, inspired by the accurate yet costly least-squares shadowing ... -
An active feedback flow control theory of the vortex breakdown process
Granata, Joshua (Rensselaer Polytechnic Institute, Troy, NY, 2014-08)Computed examples of the flow dynamics based on the full Euler and Navier-Stokes formulations at various swirl levels demonstrate the evolution to near-steady breakdown states when swirl is above a critical level which ... -
An investigation of the approximate optimal projection reduced-order models for elliptic partial differential equations
Hu, Mingyu (Rensselaer Polytechnic Institute, Troy, NY, 2016-05)Reduced-order modeling is often utilized in obtaining an approximate solution to a complex high-fidelity system. An essential step in constructing a reduced-order system is to project the original high-fidelity system onto ... -
Automated adaptive viscous flow simulations
Sahni, Onkar (Rensselaer Polytechnic Institute, Troy, NY, 2007-12) -
Busemann-sears-haack hybrid geometries applied toward supersonic commercial vehicles for improved wave drag performance
Sklar, Andrew Wallace (Rensselaer Polytechnic Institute, Troy, NY, 2019-05)In this thesis, I have presented a new configuration for supersonic aircraft fuselages. I first demonstrated that the commercial Fluent code provides mesh converged, valid results for supersonic flows around various ... -
Centrifugal jet spinning of polymer nanofiber assembly : process characterization and engineering applications
Ren, Liyun (Rensselaer Polytechnic Institute, Troy, NY, 2014-12)High surface area together with unique electrical, thermal, and mechanical properties makes polymer nanofibers suitable in various commercial sectors, including but not limited to electronics, energy, mechanical/chemical, ... -
Characterization of high speed synthetic jet actuators
Pikcilingis, Lucia (Rensselaer Polytechnic Institute, Troy, NY, 2015-12)Altering the clamping conditions, at which the disks are clamped, showed that increasing the number of clamping points where the disks are clamped, improved the performance of the jet. Coupling this with a flexible clamping ... -
Computational analysis of swirling flows in a pipe
Ochoa, Obdulio (Rensselaer Polytechnic Institute, Troy, NY, 2015-12)The vortex breakdown of a swirling jet flow entering a finite-length pipe is studied in this thesis. The theories of Rusak and co-authors which provide fundamental tools to predict the first occurrence of breakdown and simulate ... -
Computational fluid dynamics studies on the influence of fuel variability on diesel engine operation
Huang, Mingdi Michael (Rensselaer Polytechnic Institute, Troy, NY, 2015-08)A light-duty single-cylinder direct-injection diesel engine (Yanmar L100V) was modeled using the developed CFD methods to numerically investigate the influence of fuel variations on in-cylinder spray ignition. Simulations ... -
Computational methods for PDE constrained minimization problems in bio-mechanical imaging
Tyagi, Mohit (Rensselaer Polytechnic Institute, Troy, NY, 2016-08)Elasticity imaging is a collection of techniques that are used to create images of mechanical properties of tissue. In elasticity imaging, the tissue is deformed, and the corresponding displacement field within the tissue ... -
Computational methods for the dynamic compaction of porous solids
Lucier, Joseph (Rensselaer Polytechnic Institute, Troy, NY, 2016-12)A 78% dense porous aluminum material was chosen and run through a variety of simulations to predict its compaction under dynamic loadings. The results of these computations were compared to experimental data collected by ...