A procedure is presented which allows to compute in a non-invasive manner, blood viscosity through flow measurements obtained at a fixed vessel cross-section. The data set is made of measurements (artery radius and spatially discrete velocity profiles) performed at given time intervals for which the signal to noise ratio is typical of U.S. Doppler velocimetry in clinical situation. This identification approach is based on the minimization, through a backpropagation algorithm, of a cost function quantifying the distance between numerical data obtained through Navier-Stokes simulations and experimental measurements. Since this cost function implicitly depends on the value of viscosity used in numerical simulations, its minimization determines an effective viscosity which is shown to be robust to measurement errors and sampling time. Such an approach is shown to work in an in vitro experiment, and seems to be suitable for in vivo measurements of viscosity by the atraumatic techniques of Doppler echography.

The paper presents an efficient methodology to characterize electromagnetic disturbances radiated from power electronic devices. The approach is based on the substitution of an equivalent set of elemental magnetic dipoles for the real system; this set radiates the same near-field. The cartography of the magnetic field obtained with a measurement bench gives these dipoles. The moments of the dipoles are determined through a root mean squared procedure; this procedure fits the measured field to the theoretical field over a closed surface surrounding the device under test. The viability of the approach is demonstrated on two circuit boards. The first one is a canonical configuration involving two solenoidal inductors. The second one is a practical power electronic converter. Comparisons between numerical and experimental magnetic field distributions underline the ability of the equivalent model.

Accepted models of polymers in flow assume that the polymer chains stretch with the elastic energy stored as a reduced entropy of the chain. The first optical measurement of changes in the Polydiacetylene 4-Butoxycarbonylmethylurethane (4-BCMU) polymer Kuhn segment lengths in Couette flow are reported. This polymer in semi-dilute solution shows a reducing conjugated segment length with increasing flow rate. The visco-elasticity for this polymer is attributed to compressive entropy loss in the chain. This is a reversal of the physics assumed in models of polymer flow based on the Kuhn model. The restricted volume of the chain due to the presence of the neighbouring polymers results in compressive hydrodynamic forces on the chains in Couette flow at semi-dilute concentrations.

This paper deals with the new results of the distributed point source method (DPSM). This method has been first developed at the SATIE lab, located at the École Normale Supérieure of Cachan, France. This method now allows the modelling of interactions between an incident wave and an obstacle. It can be applied in the non destructive testing area, using eddy currents or ultrasonic waves.

Numerical solutions of 2-D steady incompressible flow inside a triangular cavity are presented. For the purpose of comparing our results with several different triangular cavity studies with different triangle geometries, a general triangle mapped onto a computational domain is considered. The Navier-Stokes equations in general curvilinear coordinates in streamfunction and vorticity formulation are numerically solved. Using a very fine grid mesh, the triangular cavity flow is solved for high Reynolds numbers. The results are compared with the numerical solutions found in the literature and also with analytical solutions as well. Detailed results are presented.

We present a numerical model used to compute steady flow solutions of the venous circulation of the leg. The network topology is based on clinical data and the flow is assumed to be steady, incompressible, and one-dimensional. We develop a non Newtonian approach to a one-dimensional flow because the blood viscosity depends on the velocity profile, and we demonstrate theoretically the pertinence of a phenomenological law of equivalent viscosity. Clinical experiments observe hemodynamical variables (i.e. venous pressure, venous area, blood velocity) only at the accessible places. In contrast the numerical model results are not limited to particular locations but can be evaluated on every point of the network. It provides important help to the definition of a clinical protocol. The model was designed to quantify a compression level of elastic compression stockings and to plan clinical studies. We validate the numerical approach using a published clinical trial, where the diameter of superficial and deep veins were measured at different compression pressures. We show also that the viscosity variations in a bed-rest position as a consequence of the application of a European Class II compression stockings. These variations could prevent the hyper-coagulability and the stasis of the blood.