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Fluent Overview. Goodarz Ahmadi and Kambiz Nazridoust. Department of Mechanical and Aeronautical Engineering Clarkson University Potsdam, NY 13699-5725. Run Fluent. Set Solution Parameters. Initialize. Enable Solution Monitors. Calculate a Solution. Modify the Solution
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Fluent Overview Goodarz Ahmadi and Kambiz Nazridoust Department of Mechanical and Aeronautical Engineering Clarkson University Potsdam, NY 13699-5725
Set Solution Parameters Initialize Enable Solution Monitors Calculate a Solution Modify the Solution Parameters or the Mesh Converged? No Yes Accurate? No Stop Yes Solution Procedure Overview • Solution Parameters • Choosing the Solver • Discretization Schemes • Initialization • Convergence • Monitoring Convergence • Stability • Setting Under-relaxation • Setting Courant number • Accelerating Convergence • Accuracy • Grid Independence • Adaptation
Solver Overview Menu is laid out such that order of operation is generally left to right. • Import (scale) the mesh file • Select physical models • Define material properties • Prescribe operating conditions • Prescribe boundary conditions • Provide an initial solution • Set solver controls • Set up convergence monitors • Compute and monitor solution
Mouse Functionality • Mouse button functionality depends on solver and can be configured in the solver Display Menu Mouse Buttons... • Default Settings: • 2D Solver • Left button translates (dolly) • Middle button zooms • Right button selects/probes • 3D Solver • Left button rotates about 2-axes • Middle button zooms • Right button selects/probes
node face cell 2D mesh node edge cell face 3D mesh Mesh Components • Components are defined in preprocessor • Cell = control volume into which domain is broken up • computational domain is defined by mesh that represents the fluid and solid regions of interest. • Face = boundary of a cell • Edge = boundary of a face • Node = grid point • Zone = group of nodes, faces, and/or cells • Boundary data assigned to face zones. • Material data and source terms assigned to cell zones. cell center
Reading a Mesh File How to… • File Menu Read Case
Check/Scale/Translate Mesh • Fluent assumes that all physical dimensions are initially in meters. • The default unit system in Fluent is Metric (SI) units. How to… • Grid Menu Check • Grid Menu Scale • Grid Menu Translate
View Grid How to… • Display Menu Grid
Define Models How to… • Define Menu Models Solver • Define Menu Models Viscous
Define Materials How to… • Define Menu Materials Fluent Database • Physical models may require additional material properties need to be defined. • Single-Phase, Single Species Flows • Define fluid/solid properties • Real gas model • Multiple Phase Flows (Single Species) • Define properties for all fluids and solids. • Multiple Species (Single Phase) Flows Mixture Material concept employed • Mixture properties (composition dependent) defined separately from constituent’s properties. • Component properties must be defined.
Define Materials How to… • Define Menu Materials Fluent Database
Define Boundary Conditions • To formulate a problem that results in a unique solution, the relevant variables at the domain boundaries must be defined. Specifying velocity, temperature and pressure or fluxes of mass, momentum, energy. • Defining boundary conditions involves: • identifying the location of the boundaries (e.g., inlets, walls, symmetry) • supplying information at the boundaries
Define Boundary Conditions How to… Define Menu Boundary Conditions Select Zones • Boundary Condition Types of External Faces • General: Pressure inlet, Pressure outlet • Incompressible: Velocity inlet, Outflow • Compressible flows: Mass flow inlet, Pressure far-field • Special: Inlet vent, outlet vent, intake fan, exhaust fan • Other: Wall, Symmetry, Periodic, Axis • Boundary Condition Types of Cell ‘Boundaries’ • Fluid and Solid • Boundary Condition Types of Double-Sided Face ‘Boundaries’ • Fan, Interior, Porous Jump, Radiator, Walls
Define Boundary Conditions How to… Define Menu Boundary Conditions Select Zones
Initialization How to… • Solve Menu Initialize Initialize
Solution Monitoring How to… • Solve Menu Monitors Residuals • The convergence of solution can also be changed
Solve How to… • Solve Menu Iterate Iterate
Post-Processing How to… • Display Menu Contours • Display Menu Vectors
x-Velocity = 0.85 m/s y-Velocity = 0.00 m/s Outflow 15cm 60cm Practice Example Flow in a Channel • Steady State • Inlet Velocity is known • Outlet is open to atmospheric pressure • No Slip on all walls • Fluid is Water • Desired Grid Resolution is 1500 Hexahedral Cells