A fully 3D parallel and Cartesian level set method was coupled with the volume of fluid method within the commercial CFD code FLUENT. In this CLSVOF method, the level set function was used to compute the surface tension contribution to the Navier–Stokes equations more accurately than the VOF method by itself. The volume of fluid function was then used to capture the interface. Two drawbacks of the LS and the VOF methods were overcome: the mass conservation problem of the LS method and the rather poor calculation of curvature and normal vector to the interface for the VOF method.
COBISS.SI-ID: 11485211
The flow distribution of air and water among the parallel vertical tubes of a manifold system has been studied. Data on a semicircle cross-section header of 1.22mm hydraulic diameter and three T-junctions with the corresponding side arms of 0.61mm hydraulic diameter are presented for the following flow regimes: bubbly, bubbly to slug, slug, semi-annular and churn flow. The separation effects at the individual T- junctions in a manifold accumulate, giving a phase concentration towards the downstream end of the manifold in vertical downward arm arrangement in all flow regimes except bubbly flow.
COBISS.SI-ID: 11440923
Water hammer effects caused by closure of spherical valves against the discharge are investigated. The valve closure is controlled by hydraulic servomotor. Since the torque acting on the valve body depends on flow conditions, the valve closing time varies significantly for different flow velocities (passive valve). The valve closing time results from numerical simulation, while for the active valve the closing time is assumed prior to simulation. Numerical results using both the active and the passive spherical valve models are compared with results of field measurements in hydropower plant.
COBISS.SI-ID: 11748891
In the paper, a comparison of turbulence models for internal flow s with complex geometry is shown. The grid independent study and comparison of tetrahedral and polyhedral control volumes is provided first, after that, the comparison of velocity and pressure profiles for various turbulence models is discussed
COBISS.SI-ID: 11552283
The paper presents a power analysis by mixing of water in a vessel stirred with dual impellers (composed of a Rushton turbine, RuT and a twisted blade turbine, TBT) by four geometrical configurations. Experiment results showed that the smallest power consumption was achieved by TBT/RuT configuration with a smaller clearance between the impellers while the higher clearance in the same configuration caused higher power consumption.
COBISS.SI-ID: 11550491