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Bubble Entrainment and Transport with Application to Ship Hydrodynamics.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Bubble Entrainment and Transport with Application to Ship Hydrodynamics./
作者:	Yuan, Ben.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2022,
面頁冊數:	160 p.
附註:	Source: Dissertations Abstracts International, Volume: 84-01, Section: B.
Contained By:	Dissertations Abstracts International84-01B.
標題:	Fluid mechanics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29165233
ISBN:	9798837523311

Bubble Entrainment and Transport with Application to Ship Hydrodynamics.
Yuan, Ben.

Bubble Entrainment and Transport with Application to Ship Hydrodynamics. - Ann Arbor : ProQuest Dissertations & Theses, 2022 - 160 p.

Source: Dissertations Abstracts International, Volume: 84-01, Section: B.

Thesis (Ph.D.)--The University of Iowa, 2022.

This item must not be sold to any third party vendors.

In ship hydrodynamics, bubbly flow is of significant importance as it impacts the wake acoustic and visual signatures, bubble-induced drag reduction, erosion due to cavitation, and other phenomena. Modeling has been and will still be in the foreseeable future the only feasible way of tackling the bubbly flow in ship hydrodynamics. This thesis contributes to three aspects related to the modeling of two-phase flow. The first contribution is a new method to evaluating the turbulent kinetic energy (TKE) and its dissipation rate with hybrid Reynolds-averaged Navier-Stokes (RANS)/Large eddy simulation (LES) methods. TKE and its dissipation are important inputs to most bubble entrainment and transport models but are not directly obtainable for standard hybrid RANS/LES. A spatial-temporal average method is proposed to extract the mean flow information and a new equation for specific dissipation rate is derived to predict the dissipation rate. Satisfactory agreement with experiments or DNS is demonstrated for decaying/forced homogeneous isotropic turbulence (HIT) and the more complicated flow on a backward-facing step case.The second contribution is a new bubble breakup model and an improvement to Prince and Blanch (1990) coalescence model. The proposed breakup model uses hybrid energy-force breakup criteria and a full turbulence spectrum. The collision angle effect and efficiency for large turbulent eddies are employed to improve the details of the model. A breakage size distribution function is introduced to account for the probability of each daughter volume fraction after the breakage, improving the model both numerically and physically. A full spectrum model was employed in the coalescence model to be consistent with the breakup model. When tested in two-phase HIT flows, these models predict breakup rate and equilibrium bubble size distributions in line with experimental measurements.The third contribution consists of improvements to the existing impact and turbulent entrainment models. Geometric information is now modeled into the impact entrainment model to improve its generality. The effect of air cavity and leakage is also included in the model. For the turbulent entrainment model, the single vortex entrainment model is improved using results from direct numerical simulation (DNS) of vortex/free surface interaction and entrainment from Hendrickson et al. (2022), minimizing assumptions and approximations used for this part of modeling. Turbulent vortex circulation and rise speed models from local turbulence model values are developed to integrate the DNS data into the turbulent entrainment model framework of Castro et al. (2016). While the model uses a calibration constant, a unit value provides best results, essentially freeing the model from modeling parameters. A grid convergence study for the full-scale Athena Research Vessel demonstrates that the model is independent of grid resolution for both RANS and DES, and that it is able to predict void fraction and bubble size distribution that match experimental results.

ISBN: 9798837523311Subjects--Topical Terms:

528155
Fluid mechanics.
Subjects--Index Terms:

Air entrainment

Bubble Entrainment and Transport with Application to Ship Hydrodynamics.
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245 1 0 $a Bubble Entrainment and Transport with Application to Ship Hydrodynamics.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2022
300 $a 160 p.
500 $a Source: Dissertations Abstracts International, Volume: 84-01, Section: B.
500 $a Advisor: Carrica, Pablo M;Li, Jiajia.
502 $a Thesis (Ph.D.)--The University of Iowa, 2022.
506 $a This item must not be sold to any third party vendors.
520 $a In ship hydrodynamics, bubbly flow is of significant importance as it impacts the wake acoustic and visual signatures, bubble-induced drag reduction, erosion due to cavitation, and other phenomena. Modeling has been and will still be in the foreseeable future the only feasible way of tackling the bubbly flow in ship hydrodynamics. This thesis contributes to three aspects related to the modeling of two-phase flow. The first contribution is a new method to evaluating the turbulent kinetic energy (TKE) and its dissipation rate with hybrid Reynolds-averaged Navier-Stokes (RANS)/Large eddy simulation (LES) methods. TKE and its dissipation are important inputs to most bubble entrainment and transport models but are not directly obtainable for standard hybrid RANS/LES. A spatial-temporal average method is proposed to extract the mean flow information and a new equation for specific dissipation rate is derived to predict the dissipation rate. Satisfactory agreement with experiments or DNS is demonstrated for decaying/forced homogeneous isotropic turbulence (HIT) and the more complicated flow on a backward-facing step case.The second contribution is a new bubble breakup model and an improvement to Prince and Blanch (1990) coalescence model. The proposed breakup model uses hybrid energy-force breakup criteria and a full turbulence spectrum. The collision angle effect and efficiency for large turbulent eddies are employed to improve the details of the model. A breakage size distribution function is introduced to account for the probability of each daughter volume fraction after the breakage, improving the model both numerically and physically. A full spectrum model was employed in the coalescence model to be consistent with the breakup model. When tested in two-phase HIT flows, these models predict breakup rate and equilibrium bubble size distributions in line with experimental measurements.The third contribution consists of improvements to the existing impact and turbulent entrainment models. Geometric information is now modeled into the impact entrainment model to improve its generality. The effect of air cavity and leakage is also included in the model. For the turbulent entrainment model, the single vortex entrainment model is improved using results from direct numerical simulation (DNS) of vortex/free surface interaction and entrainment from Hendrickson et al. (2022), minimizing assumptions and approximations used for this part of modeling. Turbulent vortex circulation and rise speed models from local turbulence model values are developed to integrate the DNS data into the turbulent entrainment model framework of Castro et al. (2016). While the model uses a calibration constant, a unit value provides best results, essentially freeing the model from modeling parameters. A grid convergence study for the full-scale Athena Research Vessel demonstrates that the model is independent of grid resolution for both RANS and DES, and that it is able to predict void fraction and bubble size distribution that match experimental results.
590 $a School code: 0096.
650 4 $a Fluid mechanics. $3 528155
650 4 $a Applied physics. $3 3343996
650 4 $a Naval engineering. $3 3173824
650 4 $a Computational physics. $3 3343998
653 $a Air entrainment
653 $a Computational fluid dynamics
653 $a Ship hydrodynamics
653 $a Two-phase flow
653 $a Turbulent kinetic energy
653 $a Bubble breakup model
653 $a Impact and turbulent entrainment models
690 $a 0204
690 $a 0215
690 $a 0468
690 $a 0216
710 2 $a The University of Iowa. $b Mechanical Engineering. $3 1683754
773 0 $t Dissertations Abstracts International $g 84-01B.
790 $a 0096
791 $a Ph.D.
792 $a 2022
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29165233