For reasonable accuracy in thermal transient FEA, two related, but distinct, goals must be simultaneously attained: (1) the mesh must have sufficient intrinsic temporal and spatial resolution for the problem of interest; (2) the time steps must be sized to yield proper mathematical transient behavior for that mesh. If the distinction between these needs is not fully grasped, or either point sim...

In this paper, the combination of conduction with radiation into a semitransparent medium which includes absorption, emission and scattering has been investigated. In order to Study the conduction in medium, the Non-Fourier heat conduction has been applied. In this model there is a time delay between heat flux and temperature gradient. Also, in contrast with Fourier heat conduction, the speed o...

In order to image the shear modulus in soft tissue, for medical diagnosis, given one component of measured displacements as a function of time on an imaging plane, two related direct finite element-based inversion algorithms are presented. One algorithm is based on the governing equations expressed in the frequency domain, and the other is in the time domain. The algorithms consider the complet...

We consider the behavior of inf-sup stabilization in the context of transient problems with multiple time scales. Our motivation for studying this setting is provided by reacting flows problems for which small time steps are necessary in the integration process. We show that for algorithms defined through a process wherein spatial and temporal discretizations are separated, the coupling of impl...

Extraordinarily high maximum-to-minimum gas pressure ratios appear in an oscillating closed resonator at its resonance frequency for certain resonator shapes. Using a quasi-onedimensionalmodel based on the compressibleNavier–Stokes equations and a finite volume method, we investigate the transient motion of a fluid inside oscillating axisymmetric tubes, from the quiescent condition to the perio...

A Tay lo r -Ga le rk in f i n i t e element method f o r s o l v i n g large, non l i nea r t h e r m a l s t r u c t u r a l problems i s presented. The a l g o r i t h m i s formulated f o r coupled t r a n s i e n t and uncoupled quasi s t a t i c thermal s t r u c t u r a l problems. V e c t o r i z i n g s t r a t e g i e s ensure computat ional e f f i c i e n c y . Two a p p l i c a t i ...

National Bureau of Standards Gaithersburg, MD 20899 Studies of transient wave propagation in plates were carried out to establish a basis for the impact-echo technique as a nondestructive test for flaw detection in concrete. The surface displacements caused by stress waves generated by point impact on a plate were calculated using both the Green's function solution and the finite element method...

Darcy flow is a steady-state model for laminar flow of a fluid through a porous medium. The present work proposes an extended model of laminar Darcy flow by introducing dynamic pressure and velocity to the classical formulation. The solution of the proposed time-space model is attained by discretizing the problem with a stabilized mixed Galerkin method in space and a forward Euler method in tim...

The finite-element method of analysis is unrestricted by size considerations and is well suited for the study of very small structures such as MEMS devices embedded in structures. This paper presents the numerical approach and results for a silicon-based micro-flow sensor for pulsed-flow sensing. The new approach presented here is the treatment of transient problems. A finite-element formulatio...