Zhuyin Ren

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This work addresses the construction and use of low-dimensional invariant manifolds to simplify complex chemical kinetics. Typically, chemical kinetic systems have a wide range of time scales. As a consequence, reaction trajectories rapidly approach a hierarchy of attracting manifolds of decreasing dimension in the full composition space. In previous(More)
Future MOS transistors may operate near their ballistic limits [1], so it is important to understand ballistic device physics and the prospects for achieving quasi-ballistic operation. In this paper, we explore the device design and physics issues of MOSFETs at the scaling limits using semiclassical and full quantum simulations. The device we presume is a(More)
Pulmonary embolism is the third leading cause of death in hospitalized patients in the US. Vena cava filters are medical devices inserted into the inferior vena cava (IVC) and are designed to trap thrombi before they reach the lungs. Once trapped in a filter, however, thrombi disturb otherwise natural flow patterns, which may be clinically significant. The(More)
A new dimension-reduction method, the Invariant Constrained-equilibrium Edge Pre-Image Curve (ICE-PIC) method, to simplify chemical kinetics has recently been developed by Ren et al. In the present work, the ICE-PIC method is first applied to the homogeneous autoignition of stoichiometric methane/air and its accuracy is shown to compare favorably to those(More)
Detailed chemical kinetics typically involve a large number of chemical species and a wide range of time scales. In calculations of chemically reactive flows, dimension-reduction techniques can be used to reduce the computational burden imposed by the direct use of detailed chemistry. In the reduced description, the reactive system is described in terms of(More)
Detailed chemical kinetics is an integral component for predictive simulation of turbulent flames and is important for reliable prediction of flames and emissions. Major challenges of incorporation of detailed chemistry in flame simulations are induced by the large number of chemical species and the wide range of timescales involved in detailed kinetics. In(More)
Computational calculations of combustion problems involving real fuels with chemistry represented by detailed mechanisms are prohibitive, due to the large number of species and reactions involved. We present a new combined dimension reduction and tabulation algorithm for the efficient implementation of combustion chemistry. In this algorithm, the dimension(More)
Nomenclature Roman Symbols A mapping gradient matrix with components A ij ≡ ∂f i /∂x j A maximum number of table entries per processor allowed A * critical number of ISAT table entries a number of table entries in a serial calculation a i total number of tabulated table entries in all processors in group i in the adaptive strategy a * L maximum number of(More)