The need to understand potential climate impacts and feedbacks in Arctic regions has prompted recent interest in modeling of permafrost dynamics in a warming climate. A new fine-scale integrated surface/subsurface thermal hydrology modeling capability is described and demonstrated in proofof-concept simulations. The new modeling capability combines a surface energy balance model with recently developed three-dimensional subsurface thermal hydrology models and new models for nonisothermal surface water flows and snow distribution in the microtopography. Surface water flows are modeled using the diffusion wave equation extended to include energy transport and phase change of ponded water. Variation of snow depth in the microtopography, physically the result of wind scour, is modeled phenomenologically with a diffusion wave equation. The multiple surface and subsurface processes are implemented by leveraging highly parallel community software. Fully integrated thermal hydrology simulations on the tilted open book catchment, an important test case for integrated surface/ subsurface flow modeling, are presented. Fine-scale 100 year projections of the integrated permafrost thermal hydrological system on an ice wedge polygon at Barrow Alaska in a warming climate are also presented. These simulations demonstrate the feasibility of microtopography-resolving, process-rich simulations as a tool to help understand possible future evolution of the carbon-rich Arctic tundra in a warming climate. Key Points: New permafrost thermal hydrology simulation capability is available in open-source parallel software The ATS software combines new surface and subsurface process representations in three dimensions Decadal projections of permafrost dynamics in a warming climate demonstrate the new capability Supporting Information:Supporting Information S1

Viscous flow problems exhibit boundary layers and free shear layers in which the solution gradients, normal and tangential to the flow, differ by orders of magnitude. The generalized advancing layers method is presented here as a method of generating meshes suitable for capturing such flows. The method includes several new technical advances allowing it to mesh complex geometric domains that cannot be handled by other techniques. It is currently being used for simulations in the automotive industry. Copyright © 2000 John Wiley & Sons, Ltd.

a b s t r a c tIn this paper we compare the performance of different methods for reconstructing interfaces in multi-material compressible flow simulations. The methods compared are a material-order-dependent Volume-of-Fluid (VOF) method, a material-order-independent VOF method based on power diagram partitioning of cells and the Moment-of-Fluid method (MOF). We demonstrate that the MOF method provides the most accurate tracking of interfaces, followed by the VOF method with the right material ordering. The material-orderindependent VOF method performs somewhat worse than the above two while the solutions with VOF using the wrong material order are considerably worse.

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SUMMARYThe data structure representing a mesh and the operators to create and query such a database play a crucial role in the performance of mesh generation and FE analysis applications. The design of such a database must balance the con icting requirements of compactness and computational e ciency. In this article, 10 di erent mesh representations are reviewed for linear tetrahedral and hexahedral meshes. A methodology for calculating the storage and computational costs of mesh representations is presented and the 10 data structures are analysed. Also, a system for ranking di erent data structures based on their computational and storage costs is devised and the various mesh representations are ranked according to this measure.

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