Can I reverse the direction of flow during a transient solution?
YES. With the latest version of TAS, the flow parameter MdotCp can reference array data. Therefore it can be time or temperature dependent. This can enable the flow to vary in velocity
during a transient solution. When adding array data to define the changing flow, do NOT enter a value of zero in the array data. This results in a divide by zero during the solution. Enter a
very small value like 1e-10. A negative value can be entered to represent a reversal in flow direction but in this case the fluid EXIT temperature is being defined.
To reverse the flow direction yet still define the fluid inlet temperatures, generate two flow paths, one for each direction. Generate separate inlet nodes for each flow path. The local fluid
nodes for both flow paths will be the same nodes. If the fluid inlet temperature of either flow path changes with time then the inlet boundary node can also reference array data. Make the
MdotCp value for each flow path reference the property table which in-tern references array data. The array data defined the changing MdotCp value with time. At points in time, one array
data will have a value of 1e-10, no flow, and the other will have a proper value.