A lack of complex analysis for a thermally buoyant jet in a stratified crossflow has motivated the studies presented. A computational approach using the incompressible Navier--Stokes equations (NSE) under the Boussinesq approximation is utilized. Temperature and salinity scalar transport equations are utilized in conjunction with a linear equation of state (EOS) to obtain the density field and thus the buoyancy forcing. Comparing simulation data to experimental data of a point heat source in a stratified environment provides general agreement between the aforementioned computational model and the physics studied. From the literature surveyed, no unified agreement was presented on the selection of turbulence models for the jet--in--crossflow (JICF) problem. For this reason, a comparison is presented for a standard Reynolds--Averaged Navier--Stokes (RANS) and a hybrid Reynolds--Averaged Navier--Stokes/large eddy simulation (HRLES) turbulence model. The mathematical differences are outlined as well as the implications each model has on solving a buoyant jet in stratified crossflow. The RANS model provides a general over prediction of all flow quantities when comparing to the HRLES models. Studies involving the removal of the thermal component inside the jet as well as varying the environmental stratification strength have largely determined that these affects do not alter the near-field in any significant way, at least for a high Reynolds number JICF. The velocity ratio of the jet being the ratio of the jet velocity to the free--stream flow velocity. Deviating from a velocity ratio of one has provided information on the variability of the forcing on the plate the jet exits from, as well as in the integrated energy quantities far downstream of the jet's exit. The departures presented here show that any deviation from the unity value provides an increase in the overall forces seen by the plate. It was also found that the change in the integrated potential and turbulent kinetic energies is proportional to the deviation from a unity velocity ratio. / Master of Science / A lack of complex analysis for a heated jet in a non-uniform crossflow has motivated the studies presented. A computational approach for the fluid dynamics governing equations under specific assumptions is implemented. Additional equations are solved for temperature and salinity in conjunction with a linear equation of state to obtain the density field. Comparing simulations to experimental data of a point heat source in a non-uniform, fluid tank provides general agreement between the aforementioned computational model and the physics studied. Studying the literature yields no unified agreement on the selection of turbulence treatment for the jet-in-crossflow problem. For this reason, a comparison is presented for two various techniques with differing complexity. The mathematical differences as well as the implications each model are outlined, specifically pertaining to a heated jet in a non-uniform crossflow. The simpler model provides a general over prediction when compared to the more complex model. Studies involving the removal of the heat from inside the jet as well as varying the environmental forcing have largely determined that these affects do not alter the flow field near the jet's origin point in any significant way. Changing the jet's velocity has provided information on the variability of the forcing on the plate the jet exits from, as well as in the energy released into the environment far downstream of the jet's exit. The ratios presented show that any deviation from a notional value provides an increase in the overall forces seen by the plate. It was also found that the change in the released energies is proportional to the deviation from the notional jet velocity.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/96335 |
| Date | 08 January 2020 |
| Creators | Martin, Christian Tyler |
| Contributors | Aerospace and Ocean Engineering, Paterson, Eric G., Lowe, K. Todd, Pitt, Jonathan |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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