ADVANCES IN THE PSEUDO-DNS METHODOLOGY: DATABASE CONSTRUCTION FOR THE AVERAGED INERTIAL STRESSES ON THE INTERNAL RVE

GIMENEZ JUAN; LARRETEGUY AXEL; NIGRO NORBERTO; GONZALEZ LEO; IDELSOHN, SERGIO

Santa Fe

Congreso; ENIEF 2019; 2019

AMCA - CIMEC

Pseudo Direct Numerical Simulation (pseudo-DNS) is a novel concurrent multiscale method-ology which splits the numerical solution into two: the coarse and the fine parts. Here, the coarse scalesolution is computed as usual using a relatively coarse mesh but including the pre-computed inertialstresses from the fine-scale solution. To introduce the basis of the method, in this work the pseudo-DNSmodel is first applied to the classical convection-diffusion problem. Secondly, in the context of Navier-Stokes solutions far from walls, a database for the fine-scale response is constructed. Several DNSsimulations varying the dimensionless tensor Id, which can be reduced to two parameters, are carried outon a Representative Volume Element (internal RVE) to obtain the averaged internal stresses. Numericalresults reveal that some critic Id magnitude, named Id c , can be found. The latter allows distinguishingtwo kinds of fine-scale solutions: steady state or chaotic transient solutions, i.e. with or without instabil-ities in the fluid. Therefore, a global stability analysis solving generalized eigenvalue problems is alsopresented in this work to validate the existence and the value of such Id c . Finally, the database is modeledthrough an artificial neural network to favor its computational implementation.