Abstract:
The one goal of this research is to present the adaptive mesh
refinement (AMR) technique for one dimensional two-phase slug flows.
Uniform fine meshes for these long devices are costly and, in general
situations, the optimum space discretisation could not be determined
a priori.
The adaptive mesh refinement (AMR) procedure permits this problem
to be remedied by refining the mesh locally, within regions where sharp
discontinuities and steep gradients are present. With the appropriate
algorithm and data organisation, it helps to reduce CPU time and
speed up simulations of flows in long pipes, while preserving accuracy
and acceptable execution times.
The main objective of this research is to investigate the behaviour of
the gas and non-Newtonian shear-thinning fluids in horizontal pipes.
Predictions of drag reduction ratio and holdup are presented for the
stratified flow of gas and non-Newtonian Ostwald-deWaele liquid. For
slug flow regimes, the mechanistic slug unit model is adopted in order
to estimate the pressure gradients along the slug unit. The slug unit
model is rearranged and reinterpreted as inviscid Burgers’s equation
for incompressible phases.
For both stratified and slug flow regimes, three dimensional CFD
(computational fluid dynamics) simulations were performed in order
to compare the drag reduction ratio and pressure gradients. In
stratified flows, CFD is also used in an attempt to evaluate the liquid
wall friction factor and to compare the obtained values with those
given by empirical standard correlations.The estimated pressure gradient and drag reductions are compared
with experimental data. Calculations showed an excellent agreement
between the simulation and experimental data. Shear thinning effects
are also correctly modelled in this work.
