Spelling suggestions: "subject:"computational fluid dynamics simulations"" "subject:"eomputational fluid dynamics simulations""
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Predicting Heating Rates in Hypersonic Gap FlowsLaura Haynes Holifield (13170003) 30 August 2022 (has links)
<p>A study has been undertaken to investigate the flow structure in the vicinity of discontinuities in the surface of a high-speed air vehicle. The effect of gaps and steps on aerodynamic heating is of particular interest. The present thesis presents Reynolds-averaged Navier Stokes (RANS) calculations of this class of flow. This thesis consists of two studies: a parametric study of cavity flow at Mach 2 and a study to compare with wind tunnel experiments at Mach 6. The calculations for the parametric study used the Menter two-equation SST turbulence model at fully turbulent conditions. These are two-dimensional cavity flows that were carried out to identify the influence of cavity geometry on flow structure and heating distribution inside the cavity, and to categorize cavity flow regimes. The second study employed RANS calculations for conditions corresponding to Mach 10 wind tunnel experiments carried out by Nestler et al. (AIAA Paper 1968-673) for Mach 6 boundary layer edge conditions. The SST model used in the parametric study was paired with the Menter oneequation transition model and the two-equation realizable κ-ϵ model in CFD++ was used for the computations. The results showed that, even with adjustment of model parameters, the Menter transition model cannot match the location of laminar to turbulent transition, but it demonstrated good agreement with the experimental data in fully turbulent conditions. The two-equation realizable κ-ϵ model, available in CFD++, was able to accurately model transition and showed favorable agreement for fully turbulent conditions as well.</p>
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Propellant Slosh in Conformal TanksEmily Beckman (9749552) 15 December 2020 (has links)
<div>As small satellites are increasingly used in the space industry, creative solutions for the use of their limited volume will be required. Conformal tanks are one idea to better make use of this volume. These tanks are non-traditionally shaped and non-axisymmetric. Because slosh can have detrimental effects on a spacecraft, it should be understood. However, slosh in these more complicated geometries has not been thoroughly investigated in the past.</div><div><br></div><div>This research looks at slosh within six geometries, five of which are conformal tanks. These geometries are evaluated in both an experiment and using CFD simulations. It was found that the total slosh motion appears to be the sum of slosh behavior along each dimension. Slosh along a line of symmetry will have center of mass movement that stays along that line. Slosh off the line of symmetry will deviate from that line unless slosh frequency is the same in each direction.</div>
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CFD MODELING IN DESIGN AND EVALUATION OF AN ENDOVASCULAR CHEMOFILTER DEVICENazanin Maani (8066141) 02 December 2019 (has links)
<p>Intra-Arterial Chemotherapy (IAC) is a preferred treatment
for the primary liver cancer, despite its adverse side-effects. During IAC, a
mixture of chemotherapeutic drugs, e.g. Doxorubicin, is injected into an artery
supplying the tumor. A fraction of Doxorubicin is absorbed by the tumor, but
the remaining drug passes into systemic circulation, causing irreversible heart
failure. The efficiency and safety of the IAC can be improved by chemical
filtration of the excessive drugs with a catheter-based Chemofilter device, as
proposed by a team of neuroradilogists. </p>
<p>The objective of my work was to optimize the hemodynamic and
drug binding performance of the Chemofilter device, using Computational Fluid
Dynamics (CFD) modeling. For
this, I investigated the performance of two distinct Chemofilter
configurations: 1) a porous “Chemofilter basket” formed by a lattice of
micro-cells and 2) a non-porous “honeycomb Chemofilter” consisting of parallel
hexagonal channels. A multiscale modeling approach was developed to resolve the
flow through a representative section of the porous membrane and
subsequently characterize the overall performance of the device. A heat and
mass transfer analogy was utilized to facilitate the comparison of alternative
honeycomb configurations. </p>
A multiphysics approach was
developed for modeling the electrochemical binding of Doxorubicin to the
anionic surface of the Chemofilter. An effective diffusion coefficient was
derived based on dilute and concentrated solution theory, to account for the
induced migration of ions. Computational predictions were supported by results
of <i>in-vivo</i> studies performed by
collaborators. CFD models showed that the honeycomb Chemofilter is
the most advantageous configuration with 66.8% drug elimination and 2.9 mm-Hg
pressure drop across the device. Another facet of the Chemofilter project was
its surface design with shark-skin inspired texturing, which improves the
binding performance by up to 3.5%. Computational modeling enables optimization
of the chemofiltration device, thus allowing the increase of drug dose while
reducing systemic toxicity of IAC.
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