PhD Thesis - staffweb - University of Greenwich

PhD Thesis by John Ewer.Using the group solver, the initially "dead" region is marked as Inactive resulting in the solverspending a minimum amount of effort in this region. When the second door opens after 40seconds, the Inactive region changes to Active status and the solution domain extends to coverthe second extended region. As demonstrated in the figure (See Figure 7.2.3-1), the solution justprior to the second door opening when the group solver is used is identical to the solution whenthe conventional solver is used and it is concluded that there is no loss of accuracy.FIGURE 7.2.3-2: Steady-state solution obtainedafter both doors are opened (example 1).When both doors are opened, both methods converge to the steady state solution depicted inthe figure (See Figure 7.2.3-2). However, using the conventional solver, the run time up to thepoint where the second door opens was approximately 3.02 hours while using the group solverthis was reduced to 2.72 hours, a saving of 10%. While only a modest saving, this was achievedby saving the computational effort over only a comparatively small proportion of the solutiondomain.FIGURE 7.2.3-3: Steady-state solution obtainedafter both doors are opened (example 2).7-108