Application of two‐phase fluid approach for free‐surface ship flow simulation

2002 ◽  
Vol 25 (2) ◽  
pp. 179-188 ◽  
Author(s):  
Yen‐Jen Chen ◽  
Shiu‐Wu Chau ◽  
Jen‐Shiang Kouh
2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Hamed Movahedi ◽  
Mehrdad Vasheghani Farahani ◽  
Mohsen Masihi

Abstract In this paper, we present a computational fluid dynamics (CFD) model to perform single- and two-phase fluid flow simulation on two- and three-dimensional perforated porous media with different perforation geometries. The finite volume method (FVM) has been employed to solve the equations governing the fluid flow through the porous media and obtain the pressure and velocity profiles. The volume of fluid (VOF) method has also been utilized for accurate determination of the volume occupied by each phase. The validity of the model has been achieved via comparing the simulation results with the available experimental data in the literature. The model was used to analyze the effect of perforation geometrical parameters (length and diameter), degree of heterogeneity, and also crushed zone properties (permeability and thickness) on the pressure and velocity profiles. The two-phase fluid flow around the perforation tunnel under the transient flow regime was also investigated by considering a constant mass flow boundary condition at the inlet. The developed model successfully predicted the pressure drop and resultant temperature changes for the system of air–water along clean and gravel-filled perforations under the steady-state conditions. The presented model in this study can be used as an efficient tool to design the most appropriate perforation strategy with respect to the well characteristics and reservoir properties.


Author(s):  
A. Ch. H. Kruisbrink ◽  
H. P. Morvan ◽  
F. R. Pearce

In this paper some novel Smoothed Particle Hydrodynamics (SPH) concepts are presented towards a feasibility study into the use of SPH for some aero-engine applications, e.g. for internal oil or fuel applications. A first challenge is to develop a capability to model complex wall geometries, associated with two-phase flows in gear boxes and bearing chambers for example. A demonstration is made of how such complex (for SPH) geometries can be built together with an outline of some of the wall boundary condition concepts used, including moving walls. This is an important feature for the application of SPH to engineering. Other boundary conditions are needed such as inlets, outlets and pressure boundaries, and a proper treatment of the free surface. These are outlined in the context of the proposed application. From an SPH flow simulation viewpoint, one of the challenges is to reduce the non-physical density variations arising from boundary conditions (at wall, free surface and interface), which are responsible for non-physical pressure variations and particle dynamics. The flow regimes found in the engineering systems outlined above involve droplets, filaments and films. It is therefore important to be able to handle the merging of fluids, as it is to model their interaction with another phase, which calls for appropriate multi-fluid and surface tension models. This paper introduces SPH, outlines a number of concepts listed above and presents some preliminary results towards the modeling of the KIT bearing chamber, as described by Kurz et al. [1]. This work builds on a number of numerical modeling communications made by the Nottingham team to SPHERIC, the ERCOFTAC Special Interest Group (SIG) for SPH.


Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 875
Author(s):  
Hyun-Sik Yoon ◽  
Kyung-Min Park

The present study numerically investigated the deformation of the free-surface of two-phase fluid flow in a tank which is considered as a simplified blast furnace hearth. Actually, the fluids existing in a blast furnace hearth are gas, slag and hot metal from top to bottom. However, the present study considered only gas and cold molten iron in the tank. The porosity is considered as a substitute for void volume formed by the packed bed of the particles such as cokes. The single-phase flow and two-phase fluids flow without the porosity are analyzed for comparison. The porosity contributed the free surface to forming a viscous finger near the taphole. The axi-symmetry nature of the interface of two-phase fluids flow in the cylindrical tank is broken by viscous finger as the interface instability by the gas entrainment into taphole, which has been identified by the visualization of the free surface formation. The acceleration of the free surface falling velocity and the outflow near the taphole are associated by the viscous finger by the gas entrainment. The dimensionless gas break-through time is linear with respect to the porosity magnitude.


2011 ◽  
Vol 69 (4) ◽  
pp. 842-858 ◽  
Author(s):  
Yibao Li ◽  
Eunok Jung ◽  
Wanho Lee ◽  
Hyun Geun Lee ◽  
Junseok Kim

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mariarosaria Falanga ◽  
Paola Cusano ◽  
Enza De Lauro ◽  
Simona Petrosino

AbstractIn this paper, we analyse the seismic noise at Ischia Island (Italy) with the objective of detecting the hydrothermal source signals taking advantage of the Covid-19 quiescence due to lockdown (strong reduction of anthropogenic noise). We compare the characteristics of the background noise in pre-, during and post-lockdown in terms of spectral content, energy release (RMS) and statistical moments. The continuous noise is decomposed into two independent signals in the 1−2 Hz and 2−4 Hz frequency bands, becoming sharpened around 1 Hz and 3 Hz respectively in lockdown. We propose a conceptual model according to which a dendritic system of fluid-permeated fractures plays as neighbour closed organ pipes, for which the fundamental mode provides the persistent whisper and the first higher mode is activated in concomitance with energy increases. By assuming reasonable values for the sound speed in low vapor–liquid mass fraction for a two-phase fluid and considering temperatures and pressures of the shallow aquifer fed by sea, meteoric and deep hydrothermal fluids, we estimate pipe lengths in the range 200–300 m. In this scheme, Ischia organ-like system can play both continuous whisper and transients, depending on the energy variations sourced by pressure fluctuations in the hydrothermal fluids.


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