نتایج جستجو برای: transient flow
تعداد نتایج: 599402 فیلتر نتایج به سال:
This work briefly describes our approach to visualize results of transient flow simulations in the application areas of groundwater flow and pollutant transport as well as compressible fluid flow in engine parts. The simulations use finite element data structures and can have geometries which change over time. We designed a client-server model to handle the huge amount of data that can be obtai...
In response to the need to better describe spatial variations in permeability, we designed and built a new portable field air permeameter for use on rocks in outcrop and core. In this instrument, a chamber containing a small volume of air in contact with the rock is suddenly increased in volume creating a vacuum, causing air to flow from the rock into the chamber. The instantaneous chamber volu...
A stable Alternating Direction Implicit finite-difference algorithm is used to model transient fiuid flow in heterogeneous porous media. In connection with the laboratory system for pressure transient testing of core permeability, the effects of permeability heterogeneities on the characteristics of the pressure transient were investigated. The results show that the early portion of the pressur...
Recent studies have brought into question the view that at sufficiently high Reynolds number turbulence is an asymptotic state. We present direct observation of the decay of turbulent states in Taylor-Couette flow with lifetimes spanning five orders of magnitude. We also show that there is a regime where Taylor-Couette flow shares many of the decay characteristics observed in other shear flows,...
Consider a pipeline with time dependent delivery volumes at various load points. Such a system can be controlled by changing with time the pressure setpoints at stations to manipulate flow and linepack. We present an algorithm that computes an optimum set of time-varying setpoint values (out to a user-specified simulation horizon) simultaneously for all stations. These setpoint values are compu...
We present a numerical code for calculating transient flow in plastic pipes, especially in the polyethylene pipe, to analysis water hammer phenomena. The set partial differential equations to be solved is obtained using conservation laws and behavior for the fluid and the pipe wall, associated with constitutive equations of the two media, and relationships compatibility of interfaces on velocit...
INTRODUCTION This article investigates various improvements to two existing finite volume (fv) algorithms, specifically constructed to solve transient viscoelastic flow problems. Here, we consider model problems to identify fundamental algorithmic advances. Two alternative fv-approaches are advocated and contrasted for their properties, a hybrid cell-vertex scheme and a cell-centred staggered-g...
The transient hyperaemic response in the middle cerebral artery blood flow velocity on the release of brief compression of the ipsilateral common carotid artery has been validated as an indicator of cerebral autoregulation. We evaluated, in three stages, the effect of experimental factors such as duration of compression of the common carotid artery and magnitude of the decrease in blood flow ve...
Rheological models for polymer solutions and melts based on the finitely extensible non-linear elastic (FENE) dumbbell theory are reviewed in this study. The FENE-P model that is a well-known Peterlin approximation of the FENE model, indicates noticeable deviation from original FENE predictions and also experimental results, especially in the transient flow. In addition, both FENE and FENE-P mo...
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