b'Engineer Innovation | MarineUsing Simcenter STAR-CCM+ enables simulation of the plume behavior on thefull-scale ship geometry.three-dimensional computer-aidedgeometry. The wrapper does not design (CAD) model, created andde-feature the geometry, preserving maintained by STX France inthe full details of the superstructure. collaboration with the owner and theUsing this makes setting up the model architect. This design must fulfillquick and easy, with little manual multiple requirements, both aestheticgeometry preparation required. After and practical, and vent placement andbeing imported into Simcenter STAR-design is just one of these. Cruise shipCCM+, the full-scale CAD model is superstructures are complexwrapped, meshed and set up so that geometries with detailed features on amultiple vents are modeled in the range of scales. These features cansame simulation. The same general have a significant impact on the flowmesh settings are used for all cases to patterns around the superstructureensure that the results are consistent that affect the plume dispersion,and comparable, but additional making it vital to maintain a high levelspecific mesh refinements are defined of detail in the CFD model. Thedownstream of each vent, with the Simcenter STAR-CCM+ surface wrapperlocation depending on the wind automatically creates a closed startingdirection being tested. The complete surface from the imported CADmesh has around 35 million cells, surrounding a typical ship size of 350m in length 40m wide and 65m high.Because of the highly unsteady plume dynamics, a steady Reynolds-Averaged Navier Stokes (RANS) simulation is not suitable. Instead, the detached eddy simulation (DES) hybrid modeling approach is used. The DES approach uses RANS modeling in boundary layers, but switches to a large eddy simulation (LES) model in detached (highly turbulent) flow. This gives higher accuracy in the turbulent contribution to the flow development in the areas needed, for example in the plumes. To track the concentrations of the exhausts, a multi-phase approach is used, with the output from each type of exhaust defined as a different phase. This allows multiple exhaust vents to be analyzed in the same CFD simulation, gaining maximum information from each model run. In a typical simulation, the velocity field around the ship is highly Figure 1: Typical plume dispersion in Simcenter STAR-CCM+, showing wind velocity contours (blue =turbulent, with many vortices forming slowest velocities, red = highest velocities) and an isosurface at a specified smoke mass fraction.and shedding from the superstructure. 20'