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Povaha toku modelových suspenzí
Kulaviak, Lukáš ; Večeř, Marek ; Růžička, Marek ; Drahoš, Jiří ; Hladil, Jindřich
The main object of the present investigation is to test the settling abilities of mixtures of solid particles in liquids. The key quantity here is the magnitude of the viscosity, both of the carrying liquid (water-glycerol solutions) and the effective viscosity of the two-phase mixture. Few model systems were used (glass and polystyrene pellets), to study the settling process. The sedimentation were recorded by a video camera and the resulting deposit structure was photographed. Besides, also a real suspension was tested, of geological materials (calcite, quartz, mixed geological powder, etc.). Immersion rotary viscometer Brookfield with special spindles (RVT and V spindles) was used to measure the effective viscosity of the dispersion.
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Viskozitní charakteristiky geologických suspenzí
Kulaviak, Lukáš ; Večeř, Marek ; Růžička, Marek ; Drahoš, Jiří ; Hladil, Jindřich
The system under study was real geological suspension – ground sedimentary rocks of different chemical composition (calcite, quartz, etc.) dispersed in water-glycerol solutions. The reference one-phase system was a Newtonian liquid (glycerine with water). It is problematic to measure the rheology of settling suspensions, so some specific tools must be used. We used the rotating vane rheometry, with the immersion viscometer Brookfield and two spindles V-71 and V-72. The basic rheological data of solid-liquid system are displayed as flow and effective viscosity curves. The obtained results on rheology were related to the settling behaviour of the geological mixtures, namely to the certain kind of the lateral instability.
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Hydrodynamika bubliny narážející na stěnu, experiment a modelování
Zedníková, Mária ; Vejražka, Jiří ; Růžička, Marek ; Drahoš, Jiří
The contribution deals with both experimental and theoretical investigation of collision of a bubble with a horizontal hydrophobic (glass) surface. The terminal bubble velocity, impact velocity, contact time of bubble with the wall and restitution coefficient (ratio of restitution and terminal velocity) are evaluated (by means of a high-speed camera) as a function of bubble size, which is ranging from 0.4 to 1.1 mm. The experimental results are compared with the models based on a balance of forces acting on a bubble during the interaction process. A good agreement is showed between the experimental data and theoretical predictions.
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