Developer: Oluyemi Zaccheus
MulFlow is a code that has been developed for the study of gas-liquid flows in wells and pipelines.
The code solves the one-dimensional two-phase conservation equations accounting for the gas, liquid and droplet fields. The closure relations are based on published correlations in open literature. A modification to the Andreussi and Person (1987) interfacial friction factor correlation has been implemented to properly predict the onset of liquid accumulation in slightly upward inclined pipes.
Two broad flow pattern groups are identified, namely the separated (stratified and annular) and the distributed (slug and bubble) flow group. The flow regime transition between these groups is based primarily on a minimum slip criterion. For steep downward flows however, the flow regime transition is based primarily on a maximum slip criterion.
Transients have been studied with the code by use of a fully-implicit method. This allows for time steps that are not restricted by the Courant number limitation common with semi-implicit and
explicit integration schemes.
A version of the code can be downloaded for free. It offers a simple C#-based user-friendly interface to call the MulFlow code as a point model. Flow maps based on the MulFlow mechanistic model can be generated and the hydrodynamic parameters (pressure drops, gas/liquid holdups, phase velocities, flow regimes) for a given set of input data can be determined. The closure relations are also provided as an external Matlab file; this allows the user of the GUI to change the closure relations and observe the impact on the model predictions. There is also included, along with the download, a detailed Manual document on the equations and numerical method implementation, as well as various application/validation tests.
The free downloadable version of the code can be used to study liquid loading in wells, understand multiple steady states and predict the onset of liquid accumulation in slightly upwardly inclined pipes, and predict general hydrodynamic parameters in pipelines and wells.
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