000			02114nab a2200217 4500
005			20260520003101.0
008			260224s2012 xxu ing
041			_aInglés
245	0	0	_aNumerical Investigation of Hydrodynamic Instabilities in Singing Risers
260			_a _b _cjul./ago. 2012
270			_a14/05/2013 ; 14/05/2013
300			_a21 p. ; 671-692
520			_aTraducción del resúmen del autor: Offshore transportation of gaseous fluids frequently relies on flexible pipes. Flexible pipes are obtained from the helicoidal rolling of steel tape which induces a geometrical cavity from edge to edge. Along the pipe, the gas infinitely encounters the edge to edge cavity of the same shape at regular interval. In some service conditions, acoustic vibrations of huge amplitude can arise. Indeed, in front of each cavity, there is a shear layer where Kelvin-Helmholtz instability can occur. The flow encounters a large number of cavities on its path which gives rise to a new specific problem: is there a stabilized flow? Results of large eddy scale simulations are presented as a reference but they are very costly. This gives reason to develop a numerical solution of the Orr-Sommerfeld equation in order to analyze the temporal and spatial wave lengths generated by the shear layers in front of the cavities. First, we introduce the problem of flexible risers and the analysis of some RANS and LES modeling. Second, a bibliographical study describes the state of the art about vibrations induced by cavity. Third, we state the Orr-Sommerfeld equation and set the problem we want to solve in terms of generalized eigen values Numerical discretizations are based on finite difference approaches of fourth orders. The choice of the relevant eigen values among all those provided by the solutions of the numerical problem is the main difficulty to be tackled.
581			_a4
773	0		_tOil and Gas Science and Technology _g67
942			_cARTICULO
100	1		_aBrac, J. _923781
100	1		_aBerthe, L.M. _953172
100	1		_aPradel, F. _912523
999			_c187687 _d187687