engleski

Efficient Implementation of ENO Scheme in Water Hammer Wave Modelling

Hydraulic transients can cause high pressures, which can be dangerous for the piping systems, especially in hydroelectric powerplants. During the simulation of transient pipe flow, friction losses are often estimated by using steady or quasi-steady friction terms. The velocity profiles in rapid transients significantly differ from the "steady" profiles in slowly varying transients. Since hydraulic transients can be described by the hyperbolic conservation laws and since the source term can-not be exactly evaluated due to increasingly more complicated expressions, it would be desirable to apply numerical schemes that are high order accurate. The numerical schemes satisfying the stated requirements are finite volume ENO schemes, which are used in this paper. Implementation of finite volume ENO scheme to the hydraulic transients modeling was proven to be justified. Applied one dimensional assumptions fail to capture the full three dimensional nature of the resulting damped oscillatory flow. Unsteady friction is the primary manifestation of this effect. However, conducted numerical simulations have shown to be in a good agreement with measured data. It is also worth noting that coarse grids give adequately good results compared to denser grid. Moreover, cfl number variation shows that finite volume ENO scheme produces very little numerical diffusion.

water hammer; wave modelling; ENO scheme; hyperbolic conservation laws

nije evidentirano