Radiation hydrodynamical effect

The radiation-hydrodynamic simulation includes the Quotidien EOS [29] and Ion EOS based on the Cowan model [30], For the electron component, a set of fitting formulae derived from the numerical results from the Thomas-Fermi model and a semi-empirical bonding correction [31] are adopted. The effective Z-number of the partially ionized plasma is obtained from the average atom model. Radiation transport is treated by multigroup diffusion. 

On the basis of what is the most extensive work thus far done, St Clair concluded that flocculation by a sound field may be attributed to two effects (1) To the increased effective diameter of each particle as a result of the hydrodynamic forces set up between them, and (2) the radiation pressure of the sound field causing the particles to concentrate at the antinodes. 

Hydrodynamic mechanisms are those which produce particle interactions through the surrounding fluid due to hydrodynamic forces and the asymmetry of the flow field around each particle. These mechanisms, which are not dependent on the relative differences in acoustic particle entrainments, can act from distances larger than the acoustic displacement and have to be considered as the main mechanism in the agglomeration of monodispersed aerosols, where particles are equally entrained. There are two main types of hydrodynamic mechanisms, namely mutual radiation pressure [50] and the acoustic wake effect [51,52]. The radiation pressure is a second-order effect which produces a force on a particle immersed in an acoustic field due to the transfer of momentum from the acoustic wave to the particle. This force moves the particles towards the pressure node or antinode planes of the applied standing wave, depending on the size and density of the particles. The mutual radial pressure can be computed from the primary wave as well as from other wave fields of nearby scatters. In fact, it gives rise to particle interactions as the result of forces produced on two adjacent particles by a non-linear combination of incident and scattered waves. 

Polyacrylamide El, with the lowest electrochemical degradation factor of 11.2 in Table 3, experiences the smallest reduction of resistance factor in the presence of univalent and divalent electrolytes, from 55.9 in river water to 49.5 in an 80/20 mixture of river and formation waters. These unusually large resistance factors probably resulted from the hydrodynamic resistance of the long linear polymer chain which is a unique characteristic of its gamma radiation manufacturing process. There appears to be some correspondence between the effect of electrolytes on viscosity and screen factor since polymers C and D1 with the lowest electrochemical degradation exhibit the greatest reduction in screen factor on... 

The basic processes responsible for photothermal effects in a medium are summarized in Figme 5.5. Optical radiation, usually from a laser, is absorbed in the sample, which in turn results in an increase of internal energy. This additional internal energy is dispersed by hydrodynamic relaxation, which basically means that a temperature change in the sample is observed. 

Numerous articles are available on nonlinear wave-body interaction with offshore structures.Many of these not only considers the nonlinear forces on the floating structure, but the response of the structure as well. The consistent nonlinear numerical solutions are quite elaborate and extremely time-consuming. The fully nonlinear wave-structure interaction boundary-value problem may be solved by the mixed Eulerian-Lagragian (MEL) method without any analytical approximations. This method of solution requires prohibitively large computational efforts and is not yet practical for routine industry use. Moreover, several technical issues are yet to be satisfactorily resolved before this approach can be successfully applied for complex 3D offshore structures. To address the need of the industry, several time-domain solution methods have been proposed which minimize this excessive use of computational efforts, while accounting for the so-called essential nonlinearities by some approximate means. In most cases, the hydrodynamic interaction due to radiation and diffraction effects is linearized. This allows the use of the usual 2D or 3D linear diffraction/radiation theory. 

Moreover, the free motions of the body generate the hnear hydrodynamic added mass and damping effect. In particular, the radiated potential from the body produces a 6 X 6 force matrix. When nondimensionalized by the oscillation frequency (or frequency squared) and structure displacements, the radiated forces give rise to a 6 X 6 added mass coefficient and a 6 x 6 damping coefficient matrix. 

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