Free-boundary 3D tokamak equilibria and resistive wall instabilities are calculated using a new resistive wall model in the two-fluid M3D-C1 code. In this model, the resistive wall and surrounding vacuum region are included within the computational domain. This implementation contrasts with the method typically used in fluid codes in which the resistive wall is treated as a boundary condition o...

A difficulty in the classical hydrodynamic analysis of moving contact-line problems, associated with the no-slip wall boundary condition resulting in an unbalanced divergence of the viscous stresses, is reexamined with a smoothed, finite-width interface model. The analysis in the sharp-interface limit shows that the singularity of the viscous stress can be balanced by another singularity of the...

We address the problem of acoustic propagation in waveguides with wall impedance, or Robin, boundary condition. Two improved multimodal methods are developed to remedy the problem of the low convergence of the series in the standard modal approach. In the first improved method, the series is enriched with an additional mode, which is thought to be able to restore the right boundary condition. T...

We consider the Navier-Stokes equation in a domain with rough boundaries. The small irregularity is modeled by a small amplitude and small wavelength boundary, with typical lengthscale ε ¿ 1. For periodic roughness, it is well-known that the best homogenized (that is regular in ε) boundary condition is of Navier type. Such result still holds for random stationary irregularities, as shown recent...

The general form of Maxwell’s velocity slip boundary condition for rarefied gas flows depends on both the geometry of the surface and the constitutive relations used to relate the viscous stress to rate of strain. The dependence on geometry is often overlooked in current rarefied flow calculations, and the generality of the constitutive dependence means the condition can also be usefully applie...

s: In this paper, we propose an improvement in boundary condition computation of Smoothed Particle Hydrodynamics. Generally, to calculate a wall boundary in particle methods, a wall is converted into particle representation and used as static particles. However, it has several issues, e.g., a boundary is discretized into particles and thus does not result in accurate representation of the bound...

The paper is devoted to the generalized wall functions of Robin–type and their application to near–wall turbulent flows. The wall functions are based on the transfer of a boundary condition from a wall to some intermediate boundary near the wall. The boundary conditions on the intermediate boundary are of Robin–type and represented in a differential form. The wall functions are formulated in an...

This paper analyzes the chaotic characteristics of irregular systems using both wave theory and ray theory. In ray theory, we visualize the chaotic properties of the ray propagation trajectories in a chaotic wave field. We found that the trajectory of the billiard problem with a stadium boundary condition has the same sensitivities to the initial conditions as does the mapping process on a logi...

This study investigates the time-dependent long-term creep strain in a composite cylinder made of glass/vinylester with a unidirectional ply. The cylinder is subjected to an internal pressure and the boundary condition is free–free and acts as thermal insulation. The classical lamination theory (CLT) is used to derive the governing equations as a second-order equation to determine the radial, c...

This work aims at improving an incompressible SPH model (ISPH) by adapting to it the unified semi-analytical wall boundary conditions proposed by Ferrand et al. [1]. The ISPH algorithm considered is the one proposed by Lind et al. [2]. The new description of the wall boundaries allows to impose accurately a von Neumann boundary condition on the pressure that corresponds to the impermeability co...