Density correlations in two-phase flow and fusion plasma transport

Abstract

Density fluctuations exist and propagate in two-phase flow as well as in fusion plasmas. Local flow parameters, such as velocity, mean density and the (directionally dependent) correlation length can serve to characterize a flow in a very detailed manner, including its topological structure (flow regime). Thus, determination of these parameters is an important task. This paper presents a non-intrusive correlation-based method for determination of local flow parameters. It is based on a model of the correlation structure of the flow. The method, and the model on which it is based, were developed earlier for two-phase flows with isotropic correlations. It is now extended to non-isotropic flows in which the correlation tensor can be diagonalized. With the present method it is possible to determine both axial and radial correlation lengths. Possible applications include diagnostics of non-isotropic two-phase flows as well as tokamak fusion plasmas.