Volume of fluid method

About: Volume of fluid method is a research topic. Over the lifetime, 5338 publications have been published within this topic receiving 116760 citations.

The role of diffusion on the interface thickness in a ventilated filling box

Abstract: We examine the role of diffusivity, whether molecular or turbulent, on the steady-state stratification in a ventilated filling box. The buoyancy-driven displacement ventilation model of Linden et al. (J. Fluid Mech., vol. 212, 1990, p. 309) predicts the formation of a two-layer stratification when a single plume is introduced into an enclosure with vents at the top and bottom. The model assumes that diffusion plays no role in the development of the ambient buoyancy stratification: diffusion is a slow process and the entrainment of ambient fluid into the plume from the diffuse interface will act to thin the interface resulting in a near discontinuity of density between the upper and lower layers. This prediction has been corroborated by small-scale salt bath experiments; however, full-scale measurements in ventilated rooms and complementary numerical simulations suggest an interface that is not sharp but rather smeared out over a finite thickness. For a given plume buoyancy flux, as the cross-sectional area of the enclosure increases the volume of fluid that must be entrained by the plume to maintain a sharp interface also increases. Therefore the balance between the diffusive thickening of the interface and plume-driven thinning favours a thicker interface. Conversely, the interface thickness decreases with increasing source buoyancy flux, although the dependence is relatively weak. Our analysis presents two models for predicting the interface thickness as a function of the enclosure height, base area, composite vent area, plume buoyancy flux and buoyancy diffusivity. Model results are compared with interface thickness measurements based on previously reported data. Positive qualitative and quantitative agreement is observed.

Flowmeter apparatus and method

Abstract: Disclosed are a method and apparatus for determining a quantity related to relative movement between a fluid and a body in the fluid around which the fluid divides. The relative flow past the body produces the von Karman phenomenon, wherein flow past an obstruction causes periodic fluid disturbances in the form of vortices that are shed alternately from opposite sides of the obstruction to form what is known as the Karman Vortex street in the wake of the obstruction. It should be understood that Karman vortices and related fluid disturbances are referred to as being ''''periodic'''' although they are not perfectly periodic; they are nearly periodic and have an average period. As each vortex is formed, the flow shifts somewhat from one side of the obstruction to the other producing periodic fluid disturbances in the form of fluid oscillations just ahead (upstream) of the obstruction. Spaced acoustic signals are propagated across the fluid path just ahead of or behind the object and the frequency of fluctuations in the travel time of the acoustic signals due to the von Karman related disturbances are detected as a measure related to the relative movement between the fluid and the object. Such a measure may for example be velocity of the relative movement e.g. speed of a boat, velocity of fluid through a conduit, volume of fluid flow, etc.