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Enhancement of reaction by simultaneous mixing and alignment in chaotic flow
We consider the reaction between two orientable species in a low Reynolds number flow. The reaction has the requirement that they need to be closely aligned in order to react. We suggest the appropriate framework in which to study such reaction. We explore the use of a shear-superposition micro-mixer as a device to overcome the inherent difficulties in encouraging such reaction and perform studies for a diffusive as well as a non-diffusive case. We demonstrate that it is possible to achieve simultaneous mixing of rodlike fibers and focussing of their orientation. This leads to substantial improvement in the associated reaction rates.
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Low order modeling, dynamics and control of an inert gas based fire protection system
We develop a three-parameter model for an inert-gas based fire suppression system. This consists of a two-parameter model for the discharge system coupled with a one-parameter model for the bulk dynamics in the room. We validate the model by predicting the mass discharge from the cylinder, overpressure in the room as well as temperature and pressure at a measurement location in the piping system. We develop an active control algorithm that achieves the objective of keeping the room overpressure under a specified value without significantly increasing the time of discharge relative to the uncontrolled case.
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Lagrangian averaged fluid dynamics and application to free shear layers
The Lagrangian Averaged Euler (LAE) equations are derived from the Euler equations by interchanging the usual process of applying the variational principle to derive the equations followed by averaging the equations. We study the regularization of the Euler equations and in particular, consider the regularization of the singular periodic vortex sheet roll-up problem by LAE. We find how the structures in the vortex sheet scale with the regularization parameter and also study the dispersion relation. Applications to more complex processes such as vortex merging are also considered.
Analysis and Simulation of Airflow Dynamics in a Single-room Enclosure
We analyze dynamics of momentum, heat and moisture transport in
simulations of forced convection with applications to climate
control in a simple, mechanically ventilated room. A model of
forced convection is obtained using the Boussinesq approximation,
including both the effects of humidity and temperature, and is
simulated using a finite element discretization. Simulations of
the flow and temperature fields reveals a sequence of transitions
with increasing inlet air velocity. For a fixed vertical
temperature difference, mixing and transport are dominated by
natural convection for low speeds, while large-scale
structure-driven mixing (namely, from forced convection) is
observed for higher inlet air speeds. The computation was
validated with an analytical solution for vertical flow between
infinite horizontal parallel plates with a constant temperature
difference. Airflow dynamics of the resulting recirculation zones
and unsteady flows and their effects on the indoor environment are
discussed, and scenarios for indoor climate control are presented.