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The shape is put in the sketch the way the baffles are denoted in the Fluent sketcher. Additional procedure is required to generate the mesh appropriately with the shapes in the sketch. For the standard flocculator sketch, the sketch can be partitioned to control the size of the elements along the wall of the modeled baffle. The lines can be implemented around the shapes in the sketch to control the accuracy of the mesh around the shape. The circle has another outlined just outside of the cutout of the circle to ensure accuracy of y-plus on the surfaces of the circle. The plate is implemented by partitioning the baffle into three parts across its width. The center section is the width of the plate. The case with the half cylinder has not been meshed because of difficulty to draw boundaries around the half cylinder to allow the mesher to generate uniform quadrilaterals around the shape.
Boundary layer element sizing (click for larger picture)
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This is the timescale for the simulation. The Fluent user manual states to use a fraction of the time scale for the time step size and a fraction of 10 of the timescale is a good time step size. The number of time steps gives the time elapsed in the flow. 200 time steps are used to give 20 sec worth of flow. The amount of iterations per time step is defaulted at 20. Iterations per time step between 60 and 150 were used for the multiple simulations with different positions of shapes.
Simulation of the Plate in Flocculator
Observations of the different positioning for the circle:
Layering the circle cutout in the sketch with the slightly larger circle kept the y-plus values at the surface of the circle below 5.
Diameter of the circles analysed: 0.05 m, 0.03m, 0.02m, and 0.01 m
Width of the plate analysed: 0.05 m (this simulation converged without transient analysis, possibly a result of the fixed shedding point on the plate and the plate is wide enough that the shedding flow from the edges do not interfere with one another - keeping the position of the shedding constant) .
Notes about the position of circle(s) in the simulation:
Positioning the circles before the first turn of the flocculator caused a periodic vortex shedding and variation of the turbulent energy dissipation with time in the flow around the turn that persisted and repeated in the 20 sec simulation.