Dynamics of annular gas–liquid two-phase swirling jets

Siamas, George A.; Jiang, Xi; Wrobel, L.C.

doi:10.1016/j.ijmultiphaseflow.2009.02.001

Cited by 18 publications

(14 citation statements)

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“…The density of gas ρ g , conforms to the ideal gas law (p = ρ g R g T ), and the density of water, ρ w , is assumed to be constant [16,18,33]. Since the Froude number is O(10 3 ), the body force is negligible in Eq.…”

Section: Governing Equationsmentioning

confidence: 99%

“…The turbulence kinetic energy, k, and its dissipation rate, ω, are obtained from the following transport equations [16] ∂ ∂t…”

Section: Turbulence Modelmentioning

confidence: 99%

“…For a high-speed jet, the Navier-Stokes equation is a better candidate to numerically assess the flow structures. Siamas et al [16] have assessed the dynamics of annular gas-liquid jets by direct numerical simulation. They have found that the vortex core development is dependent upon the liquid-togas density ratio of the two-phase flow.…”

Section: Introductionmentioning

confidence: 99%

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Flow structures of gaseous jets injected into water for underwater propulsion

2011

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Gaseous jets injected into water are typically found in underwater propulsion, and the flow is essentially unsteady and turbulent. Additionally, the high water-to-gas density ratio can result in complicated flow structures; hence measuring the flow structures numerically and experimentally remains a challenge. To investigate the performance of the underwater propulsion, this paper uses detailed NavierStokes flow computations to elucidate the gas-water interactions under the framework of the volume of fluid (VOF) model. Furthermore, these computations take the fluid compressibility, viscosity, and energy transfer into consideration. This paper compares the numerical results and experimental data, showing that phenomena including expansion, bulge, necking/breaking, and back-attack are highlighted in the jet process. The resulting analysis indicates that the pressure difference on the rear and front surfaces of the propulsion system can generate an additional thrust. The strong and oscillatory thrust of the underwater propulsion system is caused by the intermittent pulses of the back pressure and the nozzle exit pressure. As a result, the total thrust in underwater propulsion is not only determined by the nozzle geometry but also by the flow structures and associated pressure distributions.

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Section: Governing Equationsmentioning

confidence: 99%

“…The turbulence kinetic energy, k, and its dissipation rate, ω, are obtained from the following transport equations [16] ∂ ∂t…”

Section: Turbulence Modelmentioning

confidence: 99%

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Flow structures of gaseous jets injected into water for underwater propulsion

2011

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“…Common continuum-level viscoelastic models can capture only some limited aspect of the microscopic configurational changes. For example, the widely used FENE-P model [43] can model stretching of well-separated polymer chains in response to background shear flow, but cannot account for cross-links between chains. An alternative to the extremely difficult task of establishing a constitutive law for mucus is to devise a multiscale computational procedure that directly links microsopic and macroscopic behavior.…”

Section: Introductionmentioning

confidence: 99%

Continuum-kinetic-microscopic model of lung clearance due to core-annular fluid entrainment

Mitran

2013

Journal of Computational Physics

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The human lung is protected against aspirated infectious and toxic agents by a thin liquid layer lining the interior of the airways. This airway surface liquid is a bilayer composed of a viscoelastic mucus layer supported by a fluid film known as the periciliary liquid. The viscoelastic behavior of the mucus layer is principally due to long-chain polymers known as mucins. The airway surface liquid is cleared from the lung by ciliary transport, surface tension gradients, and airflow shear forces. This work presents a multiscale model of the effect of airflow shear forces, as exerted by tidal breathing and cough, upon clearance. The composition of the mucus layer is complex and variable in time. To avoid the restrictions imposed by adopting a viscoelastic flow model of limited validity, a multiscale computational model is introduced in which the continuum-level properties of the airway surface liquid are determined by microscopic simulation of long-chain polymers. A bridge between microscopic and continuum levels is constructed through a kinetic-level probability density function describing polymer chain configurations. The overall multiscale framework is especially suited to biological problems due to the flexibility afforded in specifying microscopic constituents, and examining the effects of various constituents upon overall mucus transport at the continuum scale.

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“…For a high speed jet, He et al 3 calculated the flow field by using the Level Set method. George et al 4 examined the dynamics of annular gas-liquid two-phase jets by means of direct numerical simulation. Cao et al 5 analyzed the dynamic characteristics of underwater supersonic gas jets at different depths, with different nozzle-expansion ratios.…”

Section: Introductionmentioning

confidence: 99%