F uel cells have tantalized engineers for more than a century as efficient devices to directly convert chemical energy to electrical energy. However, fuel cell use has been limited to niche applications, like space vehicles and emergency backup power systems, due to their expensive components and specialized fuel requirements. During the past two decades polymer electrolyte membrane (PEM) fuel ...

In order to increase the rate of gas absorption, chemical reaction in the liquid phase is considered. The purpose of this paper was to simulate gas absorption process by a liquid film over a spherical packing incorporating eddy viscosity and diffusivity. Second order chemical reaction for two different cases (fast and slow) were considered. The system partial differential equations obtained...

– We show the existence of three well defined time scales in the dynamics of wormlike micelles after a step between two shear rates on the stress plateau. These time scales are compatible with the presence of a structured interface between bands of different viscosities and correspond to the isotropic band destabilization during the stress overshoot, reconstruction of the interface after the ov...

In a dynamic weighing gas mass flow measurement, the gas mass flow rate is continuously determined by weighing a gas mass loss from a gas cylinder as a function of time. In this measurement method, the temperature difference between the wall of the gas cylinder and ambient air cannot be avoided. Due to natural convection flow, a shear stress appears on the wall of the cylinder. Because of the d...

‎in this paper‎, ‎we have investigated the chaotic behavior of thermal convection in couple stress liquid saturated porous layer subject to gravity‎, ‎heated from below and cooled from above‎, ‎based on theory of dynamical system‎. ‎a low dimensional lorenz‎- ‎like model is obtained by using galerkin-truncation approximation‎. ‎we found that there is proportional relation between scaled couple ...

In this paper, a numerical solution procedure is presented for the free and forced vibration of a piezoelectric nanowire under thermo-electro-mechanical loads based on the nonlocal elasticity theory within the framework of Timoshenko beam theory. The influences of surface piezoelectricity, surface elasticity and residual surface stress are taken into consideration. Using Hamilton’s principle, t...

The surface stability problem of an encapsulated microbubble in an ultrasound field is numerically addressed. To predict the nonlinear process, the continuity equation and Navier-Stokes equation are directly solved by means of a boundary-fitted finitevolume method on an orthogonal curvilinear coordinate system. The bubble is insonified by an ultrasound pulse consisting of a burst of 10 cycles, ...