We present a formulation of rigid body dynamics with frictional contact that leverages ideas from discrete mechanics to derive time-stepping schemes with any desired order of integration accuracy. By utilizing the new time-stepping methods as dynamics constraints in a direct trajectory optimization scheme, we are able to perform contact-implicit trajectory optimization with accuracy equal to tr...

The surface diffusion of an axi-symmetric solid, a whisker, subject to applied uniaxial stress, is studied numerically based on a new boundary integral formulation for periodic stress configurations. An efficient semi-implicit time-stepping scheme is developed to treat the serve stiffness due to high-order derivatives. When the initial perturbation is small the effect of the stress on the motio...

Implicit time stepping is often difficult to parallelize. The recently proposed Minimal Residual Approximate Implicit (MRAI) schemes [2] are specially designed as a cheaper and parallelizable alternative for implicit time stepping. A several GMRES iterations are performed to solve approximately the implicit scheme of interest, and the step size is adjusted to guarantee stability. A natural way ...

An interpolation based non-conforming spectral element atmospheric model is described. The error norms for a standard test problem are compared against uniform resolution results. Preliminary results for an adaptive mesh refinement strategy are reported. To avoid local time-stepping, a nonlinear variant of operator integration factor splitting has been implemented. A backward differentiation fo...

This work is concerned with the numerical modeling of Darcy flow and solute transport in fractured porous media for which fractures are modeled as interfaces codimension one. The hybrid-dimensional problems discretizaed by a lumped piece-wise linear finite element method, combined algebraic correction convective fluxes. resulting discretization can be interpreted conservative volume scheme that...

This paper presents a technique used to accelerate the convergence of unsteady calculations of time-periodic flows to a periodic steady state. The basis of the procedure is the use of the discrete Fourier transform in time, and is similar to the harmonic balance procedure that has been pursued by Hall et. al. The technique is amenable to parallel processing, and convergence acceleration techniq...

Convergence of a full discretization of a second order stochastic evolution equation with nonlinear damping is shown and thus existence of a solution is established. The discretization scheme combines an implicit time stepping scheme with an internal approximation. Uniqueness is proved as well.

The numerical solution for a class of sub-diffusion equations involving a parameter in the range −1 < α < 0 is studied. For the time discretization, we use an implicit finite-difference Crank–Nicolson method and show that the error is of order k2+α , where k denotes the maximum time step. A nonuniform time step is employed to compensate for the singular behaviour of the exact solution at t = 0....

Abstract: This paper presents some numerical methods for Allen-Cahn equation using different time stepping and space discretization methods with non-periodic boundary conditions. In space the equation is discretized by Chebyshev spectral method, while in time the exponential time differencing fourth-order Runge-Kutta (ETDRK4) and implicit-explicit scheme is used. For comparison we also use the ...