Gas–liquid slug flow in a horizontal concentric annulus, a comparison of numerical simulations and experimental data

Abstract

Abstract Multiphase flow simulations were run in OpenFOAM utilizing InterFoam, a volume of fluid type solver. A concentric annulus geometry was constructed and periodic boundary conditions were applied to alleviate the requirement for a longer domain. The simulations were run in 3, 5 and 7\u202fm long domains with the annulus dimensioned such that the outer and inner cylinder diameter were 0.1 and 0.05\u202fm respectively. The 4 individual mesh designs were constructed such that the coarsest mesh consists of 102k cells/m while the finest mesh was generated with 400k cells/m. Each mesh was significantly refined within 0.005\u202fm of both the inner and outer cylinder wall. The simulation data was compared with experimental pressure and holdup data collected at Institute for Energy Technology in Norway. The 3 and 7\u202fm domains reproduced slug frequencies to within 9% of the experiment results of 1.43\xa0Hz for all mesh densities. Comparatively, the 5\u202fm domain has larger errors with respect to slugging frequency (22–27%). The 5\u202fm case performs poorly, probably due to an artificial restraint introduced by the limitation of available liquid which is set as α o i l = 0.53 for all cases. The αoil restriction combined with the domain length determines the amount of liquid in the system. This interaction of factors means that the domain length is an important parameter when preparing the simulation. The pressure data display a stronger dependence on the mesh quality in comparison to the slug frequency analysis. The 3\u202fm domain with a 400k cells/m mesh resulted in a maximum and minimum pressure gradient of 1783.5 and 803.9\u202fPa/m, compared to the experiment values of 1785 and 822\u202fPa/m, which are within 3% of the expected results.