When first created, a scenario is identical to its parent. To modify or run a scenario, it must first be made in the current Workspace scenario by selecting it within the Scenario Manager window, then clicking on the Load As Current Scenario button.  (The name of the current scenario is displayed in both the Scenario Manager window and in AFT Fathom’s Status Bar.) Once a scenario is the current scenario, changes may be made to differentiate it from its parent using any of AFT Fathom’s editing tools and functions. When an attribute is changed within a scenario, it breaks the link for this attribute. Subsequent changes in the scenario’s ancestors will no longer affect this attribute.

Properties of a scenario that may differ from its ancestors include:

• Presence and location of objects -- one may add or delete pipes and junctions within a scenario and the workspace locations may vary from scenario to scenario

• Pipe and junction Properties - All values set in the Properties windows

• Fluid Properties - Fluid, viscosity model, heat transfer, and laminar and non-Newtonian corrections

• Steady Solution Control - Solution method, tolerances, relaxation

• Output Control - Output window content and formatting

• Cost Settings - Application of cost data

• Transient Control (XTS Module Only) - Start and stop times for transient simulation

• Goal Seek & Control (GSC Module Only) - Application of variables and goals can change between scenarios. The actual variables and goals are the same in all scenarios.

• Library Manager - The connected library content can be varied between scenarios

• Visual Report Control - Visual Report content and color maps

Model Data Control and User Options apply to all scenarios.