Granica laminarnego przepływu wody w obsypce żwirowej studni eksploatacyjnej

Maciej Matyka, Mariusz Mądrala

Abstrakt


The boundary of the laminar water flow in the filter pack of a pumping well.
A b s t r a c t . Structural changes of aquifers, resulting from a higher velocity of water entering a screen, may occur in the zone around wells’ screen. Well discharge rate equations assume a laminar flow and agreement with the Darcy’s law. Thus, the admissible velocity of water entering the screen should not exceed a certain limit. In this research, the microstructure of water flow velocity in the well’s filter pack was studied. We took a picture of the internal structure of the aquifer’s pore media in an in situ undisturbed soil sample. Because of the lack of a clear definition of the characteristic length scale in the Reynolds number, we propose to use additionally π – a dimensionless value describing the distribution of kinetic energy in the system – as a criterion for changing the flow nature. We based the study on numerical simulations of fluid flow in pore space. We used the Lattice-Boltzmann Method (LBM) to simulate water flow in the filtered zone. We find that in a real porous system of the filter pack with a porosity of n = 0.49, as opposed to highly porous material at n = 0.9, the values of π increase with the decreasing and increasing Reynolds number. The distribution of the velocity field in the analyzed sections also shows the formation of privileged water flow paths and the formation of vortex structures for high flow velocities.

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