Effective velocity for transport in heterogeneous compressible flows with mean drift

Effective velocity for transport in heterogeneous compressible flows with mean drift

Solving transport equations in heterogeneous flows might give rise to scale dependent transport behavior with effective large scale transport parameters differing from those found on smaller scales. For incompressible velocity fields, homogenization methods have proven to be powerful in describing the effective transport parameters. In this paper, we aim at studying the effective drift of trans...

Chaotic mixing in effective compressible flows.

We study numerically joint mixing of salt and colloids by chaotic advection and how salt inhomogeneities accelerate or delay colloid mixing by inducing a velocity drift V(dp) between colloids and fluid particles as proposed in recent experiments [J. Deseigne et al., Soft Matter 10, 4795 (2014)]. We demonstrate that because the drift velocity is no longer divergence free, small variations to the...

Lagrangian Transport Through Surfaces in Compressible Flows

A material-based, i.e., Lagrangian, methodology for exact integration of flux by volume-preserving flows through a surface has been developed recently in [Karrasch, SIAM J. Appl. Math., 76 (2016), pp. 1178–1190]. In the present paper, we first generalize this framework to general compressible flows, thereby solving the donating region problem in full generality. Second, we demonstrate the effic...

Effective Boundary Conditions for Compressible Flows over Rough Boundaries

Simulations of a flow over a roughness are prohibitively expensive for small scale structures. If the interest is only on some macroscale quantity it will be sufficient to model the influence of the unresolved microscale effects. Such multiscale models rely on an appropriate upscaling strategy. Here the strategy originally developed by Achdou et al. 1 for incompressible flows is extended to com...

A Two -Step Modification toward Implementing Compressible Source Terms in Low Compressible Flows