This work aims at comparing the accuracy and overall performance of a low-Mach CFD solver and a fully-compressible CFD solver for direct numerical simulation (DNS) of nonequilibrium plasma assisted ignition (PAI) using a phenomenological model described in Castela et al. [1]. The phenomenological model describes the impact of nanosecond pulsed plasma discharges by introducing source terms in the reacting flow equations, instead of solving the detailed plasma kinetics at every time step of the discharge. Ultra-fast gas heating and dissociation ofO2 are attributed to the electronic excitation ofN2 and the subsequent quenching to ground state. This process is highly exothermic, and is responsible for dissociation of O2 to form O radicals; both of which promote faster ignition. Another relatively slower process of gas heating associated with vibrational-to-translational relaxation is also accounted for, by solving an additional vibrational energy transport equation. A fully-compressible CFD solver for high Mach (M>0.2) reacting flows, developed by extending the default rhoCentralFoam solver in OpenFOAM, is used to perform DNS of PAI in a 2D domain representing a cross section of a pin-to-pin plasma discharge configuration. The same case is also simulated using a low-Mach, pressure-based CFD solver, built by extending the default reactingFoam solver. Themore »
This content will become publicly available on November 1, 2023
Siphon Break Phenomena Associated With Pipe Leakage Location
Abstract This work investigates the siphon break phenomenon associated with pipe leakage location. The present study is divided into two parts: (1) an unsteady three-dimensional (3D) computational fluid dynamics (CFD) model is developed to simulate the pressure head (water level) and discharge in the simulated siphon using the volume-of-fluid (VOF) technique under no-leakage condition and (2) using the model developed in the first part we investigated the siphon break phenomenon associated with pipe leakage location. The calculated results of transient water level and discharge rate at the simulated siphon for the no-leakage condition were in good agreement with the experimental measurements. In addition, the velocity, pressure fields, and phase fractions in the siphon pipe were analyzed in depth. The methodology and findings presented show that leakage above the hydraulic grade line and close to the top inverted U section of the siphon pipe ultimately leads to the siphon breakage, which is not the case for a leakage below the hydraulic grade line. It is also concluded that if leakage is above the hydraulic grade line and the leakage position is far away from the upper horizontal section of the siphon pipe, it may not lead to the immediate siphon breakage more »
- Publication Date:
- NSF-PAR ID:
- 10347143
- Journal Name:
- Journal of Fluids Engineering
- Volume:
- 144
- Issue:
- 11
- ISSN:
- 0098-2202
- Sponsoring Org:
- National Science Foundation
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