(578e) Validation of Openfoam Solver for Mixing Tank Analysis

Open source CFD tools such as OpenFOAM has gained significant attention and interest in the Industry. OpenFOAM has an extensive range of features to solve problems ranging from complex fluid flows involving chemical reactions, turbulence and heat transfer, to solid dynamics and electromagnetics. In-spite of all these capabilities its commercial use is limited because of non-availability of industry standard benchmarks. In this study, we systematically investigate the solver quality of the open source CFD code OpenFOAM for computation of the single phase as well as multiphase flow in stirred tank reactors. This study aims at discussing various case studies where OpenFOAM was successfully employed for predicting performance of stirred reactors in terms of power consumption, flow pattern, mixing time etc. The results predicted by OpenFOAM are compared with experimental data and commercial CFD tool Fluent (of ANSYS Inc.). The OpenFOAM solver was found to capture the single phase as well as multiphase flow in stirred tank with reasonable accuracy. The following case studies are discussed in this presentation.

Case – 1: In the first case the turbulent flow generated by Rushton Turbine impeller was solved using both OpenFOAM and Fluent. A mesh having combination of hexahedral and tetrahedral elements generated using Gambit (of ANSYS Inc.) was used for both the solvers. Steady state simulation was performed using MRF approach. The predicted velocities were compared with the experimentally measured velocities at various locations in the reactor.

Case – 2: In the second case study, capability of OpenFOAM solver was tested to capture the transient flow in stirred tank was using sliding mesh model. For OpenFOAM simulation a mesh generated by snappyHex mesh was used. The results predicted were compared with those predicted by Fluent using the mesh generated by Gambit.

Case – 3: In this case study, laminar non-Newtonian fluid in stirred reactor was solved using OpenFOAM and Fluent. The results were compared with respect to flow pattern, forces on impellers and baffles etc.

Case – 4: This case study focuses on testing capability of OpenFOAM solver to capture the gas entrainment in partially baffled stirred reactor. Volume of Fluid (VOF) model along with sliding mesh methodology was used to capture the entrapment of gas from headspace through the vortex. The results of OpenFOAM simulation (with snappyHex mesh) were compared with that of Fluent (using Gambit mesh).