Simulating macroscopic flows

New Approaches for Simulating Complex Flows

When it comes to simulating the flow of material mixtures, classical CFD (computational fluid dynamics) methods reach their limits. For several years now, Sulzer has been pursuing a fundamentally new approach—the Lattice-Boltzmann method—working closely with an external research partner (FlowKit SA). Sulzer uses this method to simulate specific products, and this method makes it possible to dev...

Simulating Flows Over Wavy Inclined Surfaces

Non-unique Flows in Macroscopic First-order Intersection Models

Currently, most intersection models embedded in macroscopic Dynamic Network Loading (DNL) models are not well suited for urban and regional applications. This is so because socalled internal intersection supply constraints, bounding flows due to crossing and merging conflicts inherent to the intersection itself, are missing. This paper discusses the problems that arise upon introducing such con...

Macroscopic Modeling of Turbulence in Porous Media Flows

A new model to describe turbulent flows within the porous media approximation is presented. The spatialand time fluctuations in this new model are tied together and treated as a single quantity. This novel treatment of the fluctuations leads to a natural construction of the “k” and “epsilon” type equations for rigid and isotropic porous media in which all the kinetic energy filtered in the aver...

Friction in inertial granular flows: microscopic and macroscopic origins

Granular media are prevalent in dynamic frictional processes throughout nature and technology, from earthquakes to grain transport. Empirical relations describing macroscopic friction as a function of the inertial number have proven successful in predicting experimentally observed velocity and stress profi les when combined with continuum models. However, these relations and the continuum model...