# Waterwheel shaped turbine inside a pipe simulation problem

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 December 1, 2014, 10:57 Waterwheel shaped turbine inside a pipe simulation problem #1 New Member   Mohaimin Shahed Join Date: Nov 2014 Posts: 2 Rep Power: 0 Hello Everyone, I am very new to CFD and I have carried out a simulation for a undershot waterwheel placed inside a pipeline. Currently I have used a rigid body for my waterwheel, and have two domains, one for the region surrounding the rigid body and another for the remainder of the pipe. I have specified my rotor domain as a subdomain with the option of rigid body solution and have also used a wall boundary condition for the wheel walls with the option of rigid body solution. To calculate power, I use different external torques (on the opposite direction to rotation) on the rigid body and see what my final angular velocity and try to find the optimum torque for which I have max power (Torque times angular velocity). I have attached several images to help explain what I have done. I would greatly appreciate any suggestions to help improve the accuracy of my simulation since I am not sure I am doing it right. Best Regards, Mohaimin LIBRARY: COORDINATE FRAME DEFINITIONS:PlotData.png BackView.JPG IsoView.JPG Setupview.jpg WireframeView.JPG COORDINATE FRAME: Coord 1 Axis 3 Point = 0.0[m],0.0[m],1.0[m] Coord Frame Type = Cartesian Option = Axis Points Origin Point = 0.0[m],0.0[m],0.0[m] Plane 13 Point = 1.0[m],0.0[m],0.0[m] Reference Coord Frame = Coord 0 END END MATERIAL: Crude Oil Material Group = User Option = Pure Substance PROPERTIES: Option = General Material EQUATION OF STATE: Density = 870 [kg m^-3] Molar Mass = 154 [kg kmol^-1] Option = Value END DYNAMIC VISCOSITY: Dynamic Viscosity = 0.0105 [Pa s] Option = Value END END END END FLOW: Flow Analysis 1 SOLUTION UNITS: Angle Units = [rad] Length Units = [m] Mass Units = [kg] Solid Angle Units = [sr] Temperature Units = [K] Time Units = [s] END ANALYSIS TYPE: Option = Transient EXTERNAL SOLVER COUPLING: Option = None END INITIAL TIME: Option = Automatic with Value Time = 0 [s] END TIME DURATION: Option = Total Time Total Time = 3 [s] END TIME STEPS: Option = Timesteps Timesteps = 0.025 [s] END END DOMAIN: Rotor Coord Frame = Coord 1 Domain Type = Fluid Location = B763 BOUNDARY: Default Fluid Fluid Interface Side 1 Boundary Type = INTERFACE Location = F583.763 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END MESH MOTION: Option = Stationary END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: Domain Interface 1 Side 1 Boundary Type = INTERFACE Location = RotorInterface1 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END MESH MOTION: Option = Stationary END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: RotorWall Boundary Type = WALL Location = RotorWall BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = No Slip Wall Wall Velocity Relative To = Mesh Motion END MESH MOTION: Option = Rigid Body Solution Rigid Body = Rigid Body 1 END WALL ROUGHNESS: Option = Smooth Wall END END END BOUNDARY: Symmetry Boundary Type = SYMMETRY Location = F586.763 BOUNDARY CONDITIONS: MESH MOTION: Option = Unspecified END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Displacement Relative To = Previous Mesh Option = Regions of Motion Specified MESH MOTION MODEL: Option = Displacement Diffusion MESH STIFFNESS: Option = Increase near Small Volumes Stiffness Model Exponent = 2.0 REFERENCE VOLUME: Option = Mean Control Volume END END END END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID DEFINITION: Fluid 1 Material = Crude Oil Option = Material Library MORPHOLOGY: Option = Continuous Fluid END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Option = None END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = k epsilon END TURBULENT WALL FUNCTIONS: Option = Scalable END END INITIALISATION: Option = Automatic INITIAL CONDITIONS: Velocity Type = Cartesian CARTESIAN VELOCITY COMPONENTS: Option = Automatic with Value U = 0 [m s^-1] V = 0 [m s^-1] W = 0 [m s^-1] END STATIC PRESSURE: Option = Automatic with Value Relative Pressure = 0 [Pa] END TURBULENCE INITIAL CONDITIONS: Option = Medium Intensity and Eddy Viscosity Ratio END END END SUBDOMAIN: Subdomain 1 Coord Frame = Coord 1 Location = B763 MESH MOTION: Option = Rigid Body Solution Rigid Body = Rigid Body 1 END END END DOMAIN: Stator Coord Frame = Coord 1 Domain Type = Fluid Location = B640 BOUNDARY: Default Fluid Fluid Interface Side 2 Boundary Type = INTERFACE Location = F493.640 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: Domain Interface 1 Side 2 Boundary Type = INTERFACE Location = StatorInterface1 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Conservative Interface Flux END TURBULENCE: Option = Conservative Interface Flux END END END BOUNDARY: Inlet Boundary Type = INLET Location = F486.640 BOUNDARY CONDITIONS: FLOW DIRECTION: Option = Normal to Boundary Condition END FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Mass Flow Rate = 1100 [kg s^-1] Option = Mass Flow Rate END TURBULENCE: Option = Medium Intensity and Eddy Viscosity Ratio END END END BOUNDARY: Outlet Boundary Type = OUTLET Location = F485.640 BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Mass Flow Rate = 1100 [kg s^-1] Option = Mass Flow Rate END END END BOUNDARY: Symmetry2 Boundary Type = SYMMETRY Location = F491.640 END BOUNDARY: Wall Boundary Type = WALL Location = Wall BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID DEFINITION: Fluid 1 Material = Crude Oil Option = Material Library MORPHOLOGY: Option = Continuous Fluid END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Option = None END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = k epsilon END TURBULENT WALL FUNCTIONS: Option = Scalable END END INITIALISATION: Option = Automatic INITIAL CONDITIONS: Velocity Type = Cartesian CARTESIAN VELOCITY COMPONENTS: Option = Automatic with Value U = 0 [m s^-1] V = 0 [m s^-1] W = 0 [m s^-1] END STATIC PRESSURE: Option = Automatic with Value Relative Pressure = 0 [Pa] END TURBULENCE INITIAL CONDITIONS: Option = Medium Intensity and Eddy Viscosity Ratio END END END END DOMAIN INTERFACE: Default Fluid Fluid Interface Boundary List1 = Default Fluid Fluid Interface Side 1 Boundary List2 = Default Fluid Fluid Interface Side 2 Interface Type = Fluid Fluid INTERFACE MODELS: Option = General Connection FRAME CHANGE: Option = None END MASS AND MOMENTUM: Option = Conservative Interface Flux MOMENTUM INTERFACE MODEL: Option = None END END PITCH CHANGE: Option = None END END MESH CONNECTION: Option = GGI END END DOMAIN INTERFACE: Domain Interface 1 Boundary List1 = Domain Interface 1 Side 1 Boundary List2 = Domain Interface 1 Side 2 Interface Type = Fluid Fluid INTERFACE MODELS: Option = General Connection FRAME CHANGE: Option = None END MASS AND MOMENTUM: Option = Conservative Interface Flux MOMENTUM INTERFACE MODEL: Option = None END END PITCH CHANGE: Option = None END END MESH CONNECTION: Option = GGI END END OUTPUT CONTROL: MONITOR OBJECTS: MONITOR BALANCES: Option = Full END MONITOR FORCES: Option = Full END MONITOR PARTICLES: Option = Full END MONITOR POINT: Monitor Point 1 Coord Frame = Coord 1 Expression Value = torque_z@RotorWall Option = Expression END MONITOR RESIDUALS: Option = Full END MONITOR TOTALS: Option = Full END END RESULTS: File Compression Level = Default Option = Standard END TRANSIENT RESULTS: Transient Results 1 File Compression Level = Default Option = Standard OUTPUT FREQUENCY: Option = Time Interval Time Interval = 0.075 [s] END END END RIGID BODY: Rigid Body 1 Location = RotorWall Mass = 5.15 [kg] Rigid Body Coord Frame = Coord 1 DYNAMICS: DEGREES OF FREEDOM: ROTATIONAL DEGREES OF FREEDOM: Option = Z axis END TRANSLATIONAL DEGREES OF FREEDOM: Option = None END END GRAVITY: Gravity X Component = 0 [m s^-2] Gravity Y Component = -9.81 [m s^-2] Gravity Z Component = 0 [m s^-2] Option = Cartesian Components END END INITIAL CONDITIONS: ANGULAR VELOCITY: Option = Automatic with Value xValue = 0 [radian s^-1] yValue = 0 [radian s^-1] zValue = 0 [radian s^-1] END CENTRE OF MASS: Option = Automatic END LINEAR VELOCITY: Option = Automatic with Value xValue = 0 [m s^-1] yValue = 0 [m s^-1] zValue = 0 [m s^-1] END END MASS MOMENT OF INERTIA: xxValue = 0.048 [kg m^2] xyValue = 0 [kg m^2] xzValue = 0 [kg m^2] yyValue = 0.048 [kg m^2] yzValue = 0 [kg m^2] zzValue = 0.051 [kg m^2] END END SOLVER CONTROL: Turbulence Numerics = First Order ADVECTION SCHEME: Option = High Resolution END CONVERGENCE CONTROL: Maximum Number of Coefficient Loops = 10 Minimum Number of Coefficient Loops = 1 Timescale Control = Coefficient Loops END CONVERGENCE CRITERIA: Residual Target = 1.E-4 Residual Type = RMS END TRANSIENT SCHEME: Option = Second Order Backward Euler TIMESTEP INITIALISATION: Option = Automatic END END END END COMMAND FILE: Version = 15.0 Results Version = 15.0 END SIMULATION CONTROL: EXECUTION CONTROL: EXECUTABLE SELECTION: Double Precision = Off END INTERPOLATOR STEP CONTROL: Runtime Priority = Standard DOMAIN SEARCH CONTROL: Bounding Box Tolerance = 0.01 END INTERPOLATION MODEL CONTROL: Enforce Strict Name Mapping for Phases = Off Mesh Deformation Option = Automatic Particle Relocalisation Tolerance = 0.01 END MEMORY CONTROL: Memory Allocation Factor = 1.0 END END PARALLEL HOST LIBRARY: HOST DEFINITION: winserv5 Host Architecture String = winnt-amd64 Installation Root = C:\Program Files\ANSYS Inc\v%v\CFX END END PARTITIONER STEP CONTROL: Multidomain Option = Independent Partitioning Runtime Priority = Standard EXECUTABLE SELECTION: Use Large Problem Partitioner = Off END MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARTITIONING TYPE: MeTiS Type = k-way Option = MeTiS Partition Size Rule = Automatic END END RUN DEFINITION: Run Mode = Full Solver Input File = No gap from turbine to wall but same dim.def END SOLVER STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARALLEL ENVIRONMENT: Number of Processes = 1 Start Method = Serial END END END END

 December 1, 2014, 16:11 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,701 Rep Power: 143 Have you read the FAQ on accuracy? http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

 December 2, 2014, 17:38 #3 New Member   Mohaimin Shahed Join Date: Nov 2014 Posts: 2 Rep Power: 0 Hello Ghorrocks, Thanks for your reply. I had done some sensitivity analysis with regards to grid density, turbulence model and turbulence intensity. But so far I have used smooth walls for my rigid body. For some reason inflating the region around my rigid body has not changed my results much, so I am wondering if I am doing something wrong.

 January 10, 2015, 11:19 #4 Member   Thomas Join Date: Dec 2014 Location: Poland Posts: 49 Rep Power: 11 Hi mshahed91 I have a problem, cause I try to simulate simply wind turbine to find angular velocity of rotor, but unfortunately it still fail. I created domain, subdomain, and rigid body to pattern from your CEL library.Probably the problem is cennected with mesh motion and setup with that. The question is: Could you send to me your file with this simulation of waterwheel? Also I can send to you my file with my wind turbine. Regards, Tomasz