  This article examines the use of characteristic methods in stratified
two-phase pipe flow simulations for obtaining non-dissipative flow predictions.
A Roe scheme and several methods based on the principle of characteristics are
presented for the two-fluid model. The main focus is finding numerically
efficient ways of capturing wave dynamics and flow regime transitions through
direct simulation. Characteristic methods offer the possibility of simulating
hyperbolic systems without numerical dissipation. These methods do however lack
certain fundamental conservation properties. Challenges related to information
scattering and clustering in space and time, particularly around shocks, are
also an issue in some method variants. Hybridisations with the finite volume
method are proposed which overcome these shortcomings. All methods are
compared, evaluating predictions on the onset of linear wave growth and
simulations of non-linear, discontinuous roll-waves. The following observations
are made: 1. Characteristic methods are excellent at predicting the onset of
linear hydrodynamic instability, even with a small number of computational
nodes. 2. Dissipative errors in finite volume methods and characteristic
hybrids will be closely linked to the Courant number. The Roe scheme and the
characteristic hybrids give very little dissipation error as the Courant number
approaches unity. This then becomes a question of numerical stability. 3.
Adapting dynamic grid cells, moving along with the characteristics information
drift, greatly improves simulation efficiency by allowing for longer time
steps. Dynamic grid cells are also useful for alleviating the need for
interpolation in characteristic methods. These methods easily out-perform the
more basic upwind and Lax-Friedrich schemes.
