7.1 Overview of Parallel ANSYS FLUENT

ANSYS FLUENT's parallel solver computes a solution to a large problem by simultaneously using multiple processes that may be executed on the same machine, or on different machines in a network. It does this by splitting up the computational domain into multiple partitions (Figure  7.1.1) and assigning each data partition to a different compute process, referred to as a compute node (Figure  7.1.2.) Each compute node executes the same program on its own data set, simultaneously, with every other compute node. The host process, or simply the host, does not contain mesh cells, faces, or nodes (except when using the DPM shared-memory model). Its primary purpose is to interpret commands from Cortex (the ANSYS FLUENT process responsible for user-interface and graphics-related functions) and in turn, to pass those commands (and data) to a compute node which distributes it to the other compute nodes.

Figure 7.1.1: Partitioned Mesh in Parallel ANSYS FLUENT

Figure 7.1.2: Partitioned Mesh Distributed Between Two Compute Nodes

Compute nodes store and perform computations on their portion of the mesh while a single layer of overlapping cells along partition boundaries provides communication and continuity across the partition boundaries (Figure  7.1.2). Even though the cells and faces are partitioned, all of the domains and threads in a mesh are mirrored on each compute node (Figure  7.1.3). The threads are stored as linked lists as in the serial solver. The compute nodes can be implemented on a massively parallel computer, a multiple-CPU workstation, or a network of workstations using the same or different operating systems.

Figure 7.1.3: Domain and Thread Mirroring in a Distributed Mesh