Характер деформаций на границе раздела упругих сред при условии скольжения

Fresnel coefficients obtained when solving the problem of wave propagation through the interface of two elastic media and expressions for components of the elastic-distortion tensor allow one to study the character of dynamic deformations at the interface. Deformation modes different from zero at the interface of the elastic media under the slip-contact condition have been determined. Dependences of deformation amplitudes at the interface on the wave incidence angle and parameters of the adjacent media for incident longitudinal and transverse waves have been constructed and analyzed.

Effects of Coupled Hydrodynamic in the Performance of a DP Barge Operating Close to a FPSO

In ocean systems composed by two or more closing floating bodies, coupled hydrodynamics effects must be considered. Dynamic positioned systems (DP), for example, need an accurate determination of environmental forces to guarantee a safe operation. This work presents a numerical methodology, using the WAMIT code, to evaluate both first order motions and mean drift forces of a system composed by a DP Crane Barge operating close to a turret-moored FPSO. The first order wave forces were evaluated using the code standard method. The second order forces (or mean drift forces) were obtained using the alternative control surface method. The work discussions are centered on the effects of FPSO presence on DP Barge hydrodynamics. Two relative positions between vessels were evaluated as well as three FPSO drafts (full, intermediate and ballasted). The effects of wave incidence angle were also discussed.

Further experiments on transition to Mach reflexion

Our 1975 paper reported the results of experiments on shock reflexion in a wind tunnel and a shock tube; further results are presented here. For strong shocks it is shown that transition to Mach reflexion takes place continuously at the shock wave incidence angle ω0 corresponding to the normal shock point ω0 = ωN, unless the downstream boundaries form a throat. In this event transition can be promoted anywhere within the range ω0 [les ] ωN, and it is even possible to suppress regular reflexion altogether! However when ω0 < ωN the transition is discontinuous and accompanied by hysteresis. Again for strong shocks evidence is presented which suggests that the famous persistence of regular reflexion beyond the ωN point ω0 > ωN is spurious. For weak shocks the transition condition is not known but it is found that even for regular reflexion a marked discrepancy between theory and experiment develops as the shocks become progressively weaker. Also when weak shocks diffract over single concave corners there is a somewhat surprising discontinuity in the regular reflexion range. It seems that none of these phenomena can be adequately explained by real gas effects such as viscosity and variation of specific heats.