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High-Quality Vector Field and Direct Jacobian Estimation
Gronát, Petr
In this paper, a correlation method for direct vorticity computation of the fluid velocity field is introduced. The correlation method allows an affine transformation of a correlation window. It is shown that Lagrangian field of displacements, considering the linear terms only, satisfies the requirements for affine transformation and using the Normalized-Cross-Correlation (NCC) together with affine transformation and Newton-Raphson iterative method, six parameters defining this transformation can be estimated. Using these parameters, both displacement and vorticity can be computed directly without differentiation of the vector field.
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PIV measurement of synthetic jet array
Dančová, Petra ; Vít, Tomáš ; Kotek, M.
This paper describes PIV experiments of a synthetic jet array. This part of measurements is an important step of the general study of a channel flow which is affected by synthetic jet array with emphasis on low Reynolds numbers. The study is experimental. The experiments are performed with water as the working fluids, and PIV method is used.
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Initial velocities of free-settling spherical particle
Chára, Zdeněk ; Kysela, Bohuš
The paper deals with experimental research of the initial phase of free-settling spherical particle which density is close to the density of water. The experiments were carried out with a smooth particle as well as with a particle with a rough surface. The obtained results show that in the initial phase of sedimentation, there is a formation of vortex structures, which are reflected in the increase of resistance in coefficient values.
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