MultiUQ: A software package for uncertainty quantification of multiphase flows

Abstract

multiUQ is a novel tool that simulates gas-liquid multiphase flows and quantifies uncertainty in results due to variability about fluid properties and initial/boundary conditions. The benefit over a typical deterministic solver is that inexact information, such as variability in fluid properties or flow rates, can be included to determine the affect on simulation solutions. It is common to deploy non-intrusive methods which utilize many solutions from a deterministic solver to generate a distribution of possible results. Contrarily, multiUQ uses an intrusive uncertainty quantification method wherein variables of interest are functions of space, time, and additional uncertainty dimensions. The intrusive solver is run once, giving a distribution of solutions as an output, as well as desired statistics. We use polynomial chaos to create the stochastic variables, which represent a distribution of values at each grid point. The stochastic variables are substituted into the incompressible Navier-Stokes equations, which govern the stochastic fluid dynamics. A stochastic level set is used to capture the distribution of interfaces that are present in an uncertain multiphase flow. multiUQ is written in Fortran and uses a message passing interface (MPI) for parallel operation. Given the many applications of multiphase flows, including open flows, hydraulics, fuel injection systems, and atomizing jets, there is a massive potential benefit to calculating uncertainty information about these flows in a cost-effective manner. Program summaryProgram Title: multiUQCPC Library link to program files:https://doi.org/10.17632/yp5pkd5x89.1Developer's repository link:https://bitbucket.org/markowkes/multiuqLicensing provisions: GPLv3Programming language: Fortran 95/2003Supplementary material: Wiki available at repository link.Nature of problem: Performing uncertainty quantification on simulations of gas-liquid multiphase flows to understand the impact of input uncertainty on simulation results.Solution method: This software utilizes an intrusive approach to uncertainty quantification of multiphase flows. Deterministic variables are expanded to include an added uncertainty domain by way of polynomial chaos. Stochastic Navier-Stokes govern the flow field in an incompressible one-fluid approach. Multiphase flows are created by coupling a stochastic level set and surface tension.