New Extension of Darcy's Law to Unsteady Flows

new semigroup compactifications via the enveloping semigroups of associated flows

this thesis deals with the construction of some function algebras whose corresponding semigroup compactification are universal with respect to some properies of their enveloping semigroups. the special properties are of beigan a left zero, a left simple, a group, an inflation of the right zero, and an inflation of the rectangular band.

Extension Ability of Reduced Order Model of Unsteady Incompressible Flows Using a Combination of POD and Fourier Modes

In this article, an improved reduced order modelling approach, based on the proper orthogonal decomposition (POD) method, is presented. After projecting the governing equations of flow dynamics along the POD modes, a dynamical system was obtained. Normally, the classical reduced order models do not predict accurate time variations of flow variables due to some reasons. The response of the dynam...

Unsteady Flows in Turbines

Sensitivity of unsteady collapsible channel flows to modelling assumptions

We investigate the influences of modelling assumptions on the dynamic behaviour of collapsible channel flows. The elastic wall is modelled in various different ways: as a large strain Bernoulli–Euler beam, as a small strain Timoshenko beam, and as a 2D-solid model derived from a general virtual work approach, using small strain or large strain assumptions. Different inlet boundary conditions ar...

Origin of Hysteresis in Bed Form Response to Unsteady Flows

Field and laboratory studies indicate that changes in riverbed morphology often lag changes in water discharge. This lagged response produces hysteresis in the relationship between water discharge and bed form geometry. To understand these phenomena, we performed flume experiments to observe the response of a sand bed to step increases and decreases in water discharge. For an abrupt rise in dis...