What are the Number of Increments and Number in Parallel discretisation features available for Pipe elements in Flownex? How do these features affect the simulation results, and when should they be used?
Flownex provides two discretisation features for Pipe elements: Number of Increments and Number in Parallel. The Number of Increments setting divides a pipe into smaller computational sections, allowing conservation equations to be solved over multiple segments instead of over the entire pipe length. Each increment represents a pipe section with a length equal to the total pipe length divided by the specified number of increments. Increasing the number of increments can improve solution accuracy and help achieve grid independence, particularly when modelling phenomena such as two-phase flow and water hammer. A value of 1, which is the default setting, means that the entire pipe is treated as a single computational element. Increasing the number of increments can affect predicted results such as pressure drop because property changes are captured in greater detail along the pipe length.
The Number in Parallel setting allows a user to represent multiple identical pipes operating in parallel using a single Pipe element. Instead of creating several separate parallel flow paths, the user specifies the number of parallel pipes directly in the pipe properties. This reduces model complexity, saves canvas space, and can reduce simulation setup effort. The flow is automatically distributed across the specified number of parallel pipes, increasing the effective flow area and typically reducing the pressure drop compared to a single-pipe configuration carrying the same total flow rate. The default value is 1, representing a single pipe. A pipe with a Number in Parallel value greater than 1 produces equivalent results to an explicitly modelled set of identical parallel pipes.