Module no. ME7724 |
Computational Fluid Dynamics for Engineering Applications |
Assignment 1, TB1–Week 5, Nov. 2015 |
Faculty of Science, Engineering and Computing
Table of Contents
List of Figures
Figure 1- Laminar flow through a circular pipe 2
Figure 2- Flow velocity profile through a circular pipe 6
Figure 3- Flow between two parallel plates 7
Figure 4- Flow domain and boundary conditions sketch 9
Figure 5- Flow velocity profile between two parallel plates 11
Figure 6- Flow velocity profile and effect of moving upper plate with different velocities 11
Figure 7- Flow domain and boundary conditions sketch 13
Figure 8- Flow velocity profile between two parallel plates at dp/dx= -2 Pa/m 14
Figure 9- Flow velocity profile between two parallel plates at different dp/dx 15
Figure 10- Flow velocity profile and effect of moving upper plate with different velocities 15
Figure 11- Fluid domain geometry 18
Figure 12- First trial with default meshing 18
Figure 13- Poor results of the first meshing trial 18
Figure 14- Meshing geometry trial 19
Figure 15- Final mesh geometry 19
Figure 16- First trial at orthogonal quality check 21
Figure 17- Final trial orthogonal quality check 22
Figure 18- Skewness quality check 22
Figure 20- velocity stream line 24
List of Tables
Table 1-Final mesh properties 20
Table 3 – Mesh name selected 20
Table 5- First trial meshing statistics 21
Table 6- Final trial meshing statistics and orthogonal quality 21
Table 7- Final trial meshing statistics and Skewness 22
Table 11- comparison of different first layer thickness and velocity profile 26
Question 1
Analytical solutions of laminar flow through a circular pipe can be derived by solving the simplified 3-D NS governing equations in cylindrical form.
Note: Axis in Figure 1 will be changed to z-r axis
(1.a)
To simplify the 3-D unsteady compressible NS equations to axisymmetric 2-D steady Incompressible laminar flow equations. Ignore the effects of gravity.
General Assumptions:
Steady flow.
Incompressible fluid.
Laminar and fully developed flow in z direction.
2D flow.
First, for 3D unsteady compressible Mass Conservation-continuity equation:
Steady means no change with time,
Incompressible means constant density, .
Laminar and fully developed flow in z direction so flow is parallel to the walls sides.
Pipe walls are stationary and no slip constraint at the pipe walls, at pipe walls.
Velocity only function of r, varies only with r direction (fully developed flow).
2D means only in r and z plane and no variation in direction.
.
Since,
Second, for 3D unsteady compressible Momentum equations:
In r-momentum
In -momentum
In z-momentum
Shear stress constitutive equations:
,
,
,
Incompressible means, constant density.
Steady means flow parameters do not change with time.
Laminar and fully developed flow in z direction so flow is parallel to the walls sides.
Pipe walls are stationary and no slip constraint at the pipe walls, .
Velocity only function of r, varies only with r direction (fully developed flow).
2D means only in r and z plane and no variation in direction.
Ignoring the effect of gravity, Fz and Fr equal Zero.
Third, applying all the previous conditions on the Shear stress constitutive equations:
,
,
,
Fourth, applying all the previous conditions on the momentum equations only in r and z direction:
In r-momentum
In z-momentum
(1.b)
First, Boundary conditions
Incompressible means constant density.
Steady means flow parameters do not change with time.
Laminar and fully developed flow in z direction so flow is parallel to the walls sides.
Pipe walls are stationary and no slip constraint at the pipe walls, .
Velocity only function of r, varies only with the r (fully developed flow).
2D means only in r and z plane and no variation in direction.
Ignoring the effect of gravity Fz and Fr equal Zero.
Second, by using the equation in question (1.a) for 2D steady laminar incompressible Mass Conservation-continuity equation:
Since,
Third, by using the equation in question 1.a for 2D steady laminar incompressible Momentum equations
In r-momentum
In z-momentum
Fourth, at Boundary conditions
By double integration;
And
So the velocity equation at any point in r direction is;
The Graph shows the distribution of velocity through the circular pipe diameter 2R=2m. First, the flow is driven by a pressure gradient dp/dz=1, if dp/dz<0 the velocity profile will be in the negative direction and in case of zero pressure gradient the velocity will be zero at any point in r direction (no flow). Second, the velocity profile is only function of r in a parabolic velocity profile. Third, as there is no slip condition at the pipe walls, the velocity of fluid close to the pipe walls equal zero. However, the maximum velocity can be found at the centre line of the pipe.
Fifth, Volumetric flow rate Q
The volumetric flow rate can be calculated be integrating the velocity profile over the cross sectional area of the circular pipe.
…. for circular Pipe
at R
From the volumetric flow rate equation Q,
Q increases as the quadratic radius of the pipe increase.
Q decrease as the fluid viscosity increase.
Q is directly proportional to the pressure gradient.
Fifth, Average or mean velocity
For fully developed laminar flow means
Maximum velocity at the centreline at r=0, as discussed in figure 2.
Question 2
Using Cartesian coordinate, you are asked to simplify the full 3-D unsteady compressible NS to 1-D steady incompressible laminar flow equations. You should include key steps and reasons for simplifications
(2.a)
To simplify the 3-D unsteady compressible NS equations to 1-D steady Incompressible laminar flow equations. Ignore the effects of gravity;
General Assumptions:
Axis as in Figure 3, x-y-axis.
Steady flow.
Incompressible flow.
Laminar and fully developed flow.
1D means only in x.
First, for 3D unsteady compressible Mass Conservation-continuity equation:
Second, for 3D unsteady compressible Momentum equations:
In x-momentum
In -momentum
In z-momentum
Shear stress constitutive equations for 1D (only in x):
Incompressible means , constant density.
Steady no change with time.
Flow is infinite in the z-x plane and fully developed flow means only depend on y.
1D means only in x plane and no variation in direction, .
Ignoring the effect of gravity at Fx.
Third, Applying those condition on the Shear stress constitutive equations:
Fourth, applying those conditions on Mass Conservation-continuity equation only in x direction:
Fifth, applying those conditions on the momentum equations only in x direction:
As P only function of x
(2.b)
Considering the boundary conditions (fixed bottom plate/wall, moving upper plate at constant
Velocity V, zero pressure gradient along streamwise direction, dp/dx=0).
First, Boundary conditions
Incompressible means , constant density.
Steady no change with time.
, flow is infinite in the z-x plane and fully developed flow means only depend on y.
The lower plat in fixed and no slipping condition at both plates/walls.
2D means flow only in x and y direction, .
dp/dx=0.
Ignoring the effect of gravity, Fy and Fx equal Zero.
(2.b.i)
Second, by using the equation in question (2.a) but for 2D steady laminar incompressible Mass Conservation-continuity equation
Since,
Third, by using the equations in question (2.a) but for 2D steady laminar incompressible Momentum equations
In x-momentum
Since
Therefore;
In y-momentum
Therefore P is only a function of x: = constant=0
Fourth, at Boundary conditions
By double integration;
Equation number 1:
Equation number 2:
By adding then subtracting equations 1 and 2 together,
,
The graph at figure 5 shows the flow velocity profile with the relation between the velocity in the x-axis and the distance between the two plates (2h). As there is zero pressure gradient along the stream wise direction, the velocity profile of Ux(y) is liner velocity profile. With no slipping condition, the maximum velocity of the fluid found at the moving upper plate however for the minimum velocity found at the fixed bottom plate. The velocity profile is mainly affected by the plate velocity and the distance between both plats.
Figure 1- Flow velocity profile and effect of moving upper plate with different velocities
The graph at figure 6, shows the effect of different velocity of the moving upper plate. First, with higher upper plate velocity as discussed in figure 5 the velocity profile still liner but with smaller slop value. Second, with negative velocity at the upper plate moving in the opposite direction the velocity profile still laminar but in the opposite negative direction. Third, at zero upper plate velocity and the pressure gradient is zero along the stream wise direction, there will not be any fluid motion as the flow is only driven by the upper moving plate.
(2.b.ii)
Fifth, Volumetric flow rate Q
……… dA=dydz
Q is directly proportional with the moving plate velocity and the distance between both plates.
Sixth, Mean velocity
or
Maximum velocity is at the upper moving plate =0.2m/s.
Seventh, Reynold number
Density of water at 20°c = 998.2
Dynamic viscosity of water at 20°c =
Re < 2300, therefore it’s a laminar flow
(2.c)
Considering the boundary conditions (fixed bottom plate/wall, moving upper plate at constant velocity V, and a constant pressure gradient along streamwise direction.
First, Boundary conditions
Incompressible means , constant density.
Steady no change with time.
, flow is infinite in the z-x plane and fully developed flow means only depend on y.
2D means only in x and y direction.
The lower plat in fixed and no slipping condition at both plates/walls.
Ignoring the effect of gravity Fy and Fx equal Zero.
dp/dx=-2.
Dynamic viscosity of water at 20°c =.
(2.c.i)
Second, by using the equation in question (2.a) but for 2D steady laminar incompressible Mass Conservation-continuity equation
Since
Third, by using the equations in question (2.a) but for 2D steady laminar incompressible Momentum equations
In x-momentum
In y-momentum
So P is only a function of x therefore,
Fourth, at Boundary conditions
By double integration;
Equation number 1:
Equation number 2:
Figure 8- Flow velocity profile between two parallel plates at dp/dx= -2 Pa/m
By adding then subtracting equations 1 and 2;
The graph at figure 8 shows the flow velocity profile with the relation between the velocity in the x-axis and the distance between the two plates (2h). At (-2 pressure gradient) along the stream wise direction with the same velocity direction of the upper moving plate. The fluid reach the maximum velocity 0.225 m/s slightly higher compared to the velocity of the moving plate 0.2 m/s at a location between the upper moving plate and half the distance between both plates. The velocity Ux(y) between the two plates will be positive velocity parabolic profile.
Figure 2- Flow velocity profile between two parallel plates at different dp/dx
Figure 3- Flow velocity profile and effect of moving upper plate with different velocitiesFigure 4- Flow velocity profile between two parallel plates at different dp/dx
Figure 5- Flow velocity profile and effect of moving upper plate with different velocities
Figure 6 – Fluid domain geometryFigure 7- Flow velocity profile and effect of moving upper plate with different velocitiesFigure 8- Flow velocity profile between two parallel plates at different dp/dx
Figure 9- Flow velocity profile and effect of moving upper plate with different velocitiesFigure 10- Flow velocity profile between two parallel plates at different dp/dx
As discussed in figure 8 the flow velocity properties in case of (-2 pressure gradient) along the stream wise direction with the same velocity direction of the upper moving plate, on the other hand, figure 9 shows that at positive 2 pressure gradient a backflow will appear at a location between the lower fixed plate and half the distance between both plates that means that the velocity of the upper moving plate not high enough to overcome the opposite direction of the pressure gradient. The velocity between the two plates will be negative velocity parabolic profile of Ux(y). For zero pressure gradient will be as discussed at figure 5 flow will be only driven by the velocity of upper moving plate.
Figure10 – Flow velocity profile and effect of moving upper plate with different velocities
Figure 11 – Fluid domain geometryFigure 12- Flow velocity profile and effect of moving upper plate with different velocities
Figure 13 – Fluid domain geometry
Figure 14- First trial with default meshingFigure 15 – Fluid domain geometryFigure 16- Flow velocity profile and effect of moving upper plate with different velocities
Figure 17 – Fluid domain geometryFigure 18- Flow velocity profile and effect of moving upper plate with different velocities
The graph at figure 10 shows the flow velocity profile with the relation between the velocity in the x-axis and the distance between the two plates (2h). At (-2 pressure gradient) along the stream wise direction with the same velocity direction of the upper moving plate. At higher upper plate velocity the maximum flow velocity will occur at the upper moving plate. With opposite plate direction at the same velocity (-0.2 m/s), the velocity of the upper moving plate is not high enough to overcome the opposite direction of the pressure gradient as discussed at figure 6. In case of two fixed plate, the velocity Ux profile is only function of y in a parabolic velocity profile and for Minimum velocity as there is no slip condition at the plates/walls the velocity of fluid close to the two fixed plates equal zero. However, the maximum velocity can be found at half distance between both fixed plates.
Fifth, Volumetric flow rate Q
………..
(2.c.ii)
Fifth, Volumetric flow rate Q
Dynamic viscosity of water at 20°c =
From the volumetric flow rate equation Q the following have been recognized;
Q increases as the distance between two plates increase.
Q decrease as the fluid viscosity increase.
Q is directly proportional to the pressure gradient.
Q increase as the moving plate velocity increase.
Sixth, Mean velocity
Seventh, Reynold number
Density of water at 20°c = 998.2
Dynamic viscosity of water at 20°c =
4000> Re > 2300, therefore its transient flow
Question 3
Use the available meshing tools in ANSYS to generate mesh for the two-dimensional flow over an airfoil (either S814 or S815) at low-speed (i.e. no shock wave on airfoil surfaces).
The generated mesh should reflect the key physical flow features, e.g. viscous boundary layer, rapid changes in flow field, etc. Also discuss and comment on mesh quality.
Part 1
Task (3.1)
Assumption:
The Fluid medium is air
Temp 25c
At low-speed (Subsonic)
S814 airfoil, chord length equal 1m
Air flow speed:
At Mach number is < 1, the flow speed is subsonic.
At 25 °c
K=1.4
Molecular mass M= 28.966 g/mol
Gas constant R=8.314472
Absolute Temp. T=273+25=298k
Assumed flow speed (inlet velocity) equal 5m/s.
Task (3.2)
Reynolds number:
L = 1m, the chord length of the airfoil
Task (3.3)
Low Reynolds number rang from 10x to 5x, Critical Reynold value 50x greater than this value the flow start change to turbulent flow.
So the flow is laminar throughout.
Part 2, ANSYS CFX modelling
By using ANSYS CFX16.2 (Academic)
First, Geometry:
The geometry of the airfoil was created by forming a surface from points imported by the airfoil coordinates points file given in lecture for S814 airfoil, the number of points is 65. Those points are connected together forming a curve then forming one surface. After that the surface have been extruded with a small value 0.01m as a unit length in Z direction forming 1 frozen body.
The chord length of the airfoil equal 1m and located about 3m from the edge of the air foil to the left (inlet) side of the fluid domain which is in a rectangle shape domain with dimensions 12mx6m. The fluid domain dimension gives a sufficient domain size to study the behaviour of the flowing fluid and how it will behave just before, all over and after the airfoil, the length of the modelled fluid domain is longer in case of any long, turbulent waves and to show when the fluid we go back to it is stable state.
The rectangle sketch have been extruded with dimension 0.01m that formed a frozen body after that the airfoil body is subtracted from the rectangular body (fluid domain) as shown in figure 11.
Second, Meshing:
Number of trials have been done during the creation of the last submitted mesh trial. Extra care have been taken to simulate the close area around the airfoil and the boundary layer by adding inflation layers and changing element size.
Starting from the default meshing by using all the default setting as in figure 12 and noticed how poor meshing can affect the final result as in figure 13.
Number of modifications have been done on the geometry to get finer element size at the interested area as shown in figure 14 for one of the trials. At the final modification, A circle shape geometry which reflect the airfoil curvature with diameter 3m from the assumed centre of the airfoil about 0.32m from the front edge of the airfoil and a rectangle geometry reflect the expecting the outlet stream line configuration starting almost after the end of the airfoil till the end of the domain with height 0.6 m, those two geometry sketches have been extruded with the same thickness 0.01m as shown in figure 15.
Figure 19- Meshing geometry trial
Figure 15- Final mesh geometry
Figure 20- First trial at orthogonal quality checkFigure 21- Final mesh geometry
Figure 22- First trial at orthogonal quality check
Figure 23- Final trial orthogonal quality checkFigure 24- First trial at orthogonal quality checkFigure 25- Final mesh geometry
Figure 26- First trial at orthogonal quality checkFigure 27- Final mesh geometry
Through all the attached meshing trials files, sizing function, inflation layers option and properties are what have been changed from one trial to another to reach better result and better quality mesh.
In the final mesh advanced size function have been used on curvature and specify the value of curvature normal angle that control the element edge how to span specially on the fine curvature part of the airfoil final angle was 8°. Span angle centre is fine (36° to 12°).
Max face size and max element size is 0.10m.
Meshing body size set to be automatic method.
For inflation layers position, trials have been done using smooth transition and first layer thickness. At the last mesh first layer thickness was used with thickness 0.004m. The inflation layers boundary all over the airfoil edge with number 11 layers.
The final mesh properties as shown in Table 1, 2 and 3.
Defaults |
|
Physics Preference |
CFD |
Solver Preference |
CFX |
Relevance |
0 |
Sizing |
|
Use Advanced Size Function |
On: Curvature |
Relevance Center |
Fine |
Initial Size Seed |
Active Assembly |
Smoothing |
High |
Transition |
Slow |
Span Angle Center |
Fine |
Curvature Normal Angle |
8.0 ° |
Min Size |
Default (2.0138e-003 m) |
Max Face Size |
0.10 m |
Max Size |
0.10 m |
Growth Rate |
Default (1.20 ) |
Minimum Edge Length |
3.9987e-003 m |
Element Midside Nodes |
Dropped |
Straight Sided Elements |
|
Number of Retries |
0 |
Extra Retries For Assembly |
Yes |
Rigid Body Behavior |
Dimensionally Reduced |
Mesh Morphing |
Disabled |
Statistics |
|
Nodes |
50720 |
Elements |
25193 |
Object Name |
Automatic Method |
||
State |
Fully Defined |
||
Scope |
|||
Scoping Method |
Geometry Selection |
||
Geometry |
1 Body |
1 Face |
|
Definition |
|||
Suppressed |
No |
||
Method |
Automatic |
|
|
Element Midside Nodes |
Use Global Setting |
|
|
Type |
|
Body of Influence |
|
Bodies of Influence |
|
2 Bodies |
|
Element Size |
3.e-002 m |
|
|
Growth Rate |
|
1.20 |
1.2 |
Local Min Size |
|
Default (2.0138e-003 m) |
|
Boundary Scoping Method |
Geometry Selection |
||
Boundary |
2 Edges |
||
Inflation Option |
First Layer Thickness |
||
First Layer Height |
4.e-003 m |
||
Maximum Layers |
11 |
||
Inflation Algorithm |
|
Pre |
Object Name |
inlet |
||||
State |
Fully Defined |
||||
Scope |
|||||
Scoping Method |
Geometry Selection |
||||
Geometry |
1 Face |
2 Faces |
1 Face |
||
Definition |
|||||
Send to Solver |
Yes |
||||
Visible |
Yes |
||||
Program Controlled Inflation |
Exclude |
||||
Statistics |
|||||
Type |
Manual |
||||
Total Selection |
1 Face |
2 Faces |
1 Face |
||
Suppressed |
0 |
||||
Used by Mesh Worksheet |
No |
Meshing quality check
Mesh Information |
|
Wedges | 135 |
Hexahedra | 25058 |
First, at the orthogonal quality comparison between the last two meshing trials, Meshing Statistics at the first quality check trial as shown in Table 5.
Mesh statistics |
|
Nodes | 91172 |
Elements | 45456 |
Mesh Metric | Orthogonal Quality |
Min | 2.428E-02 |
Max | 0.999 |
Average | 0.986 |
Table 5- First trial meshing statistics
Figure 16- First trial at orthogonal quality check
The orthogonal quality is ranged from 0 to 1. Value of 1 is the best orthogonal quality and it is advised to keep Min Orthogonal quality above 0.05. The minimum orthogonal quality 0.024 less than 0.05 as shown in the Table 5. At figure 16, the poor quality mesh have been identified almost at the inflation layers.
To achieving minimum orthogonal quality >0.05, some modification have been done. First layer thickness at the inflation layer changed from to 0.04m. Number of Inflation layers changed from 12 to 11.Curvature normal angel decreased to 8° which increase the refinement around the curved edge of the airfoil.
Mesh Statistics |
|
Nodes |
50720 |
Elements |
25193 |
Mesh Metric |
Orthogonal Quality |
Min |
8.018E-02 |
Max |
0.999 |
Average |
0.9776 |
Figure 17 and Table 6 shows the final meshing statistics, the min orthogonal quality above 0.05.
Table 6- Final trial meshing statistics and orthogonal quality
Figure 17- Final trial orthogonal quality check
Second, at skewness check table 7, shows mesh statistics.
Mesh Statistics |
|
Nodes |
50720 |
Elements |
25193 |
Mesh Metric |
Skewness |
Min |
2.6026e-003 |
Max |
0.95426 |
Average |
0.12941 |
Table 7- Final trial meshing statistics and Skewness
The average value is in the excellent range but on the other hand, the Max value is 0.95 which is considered as a poor quality. As shown in figure 18, only two element had been identified with this value.
Figure 18- Skewness quality check
Third at smoothness and aspect ratio, almost all changes in mesh sizes were gradual and the aspect ratio of the longest edge length to the shortest edge length not greater than 20% as shown in table 9
Mesh Statistics |
|
Min edge length ratio |
1.1335 |
Max edge length ratio |
19.4501 |
Third, Setup and Boundaries:
As shown at figure19,
At the default domain: Domain type is fluid (air), incompressible at fixed temperature 25 °c with pressure 1 atm. Using Turbulence model shear stress transport (SST) gives highly accurate result near walls and prediction of any flow separation, wall function set to be automatic.
Inlet domain: the inlet left side face of the rectangular fluid domain.
Subsonic flow with velocity components u=5m/s, v=w=0 m/s
Turbulence medium intensity = 5% as there is no information about the inlet turbulence.
Outlet domain: Opening type – the open three sides of the rectangular fluid domain.
Walls: symmetry type – two symmetry walls side of the rectangular fluid domain.
Domain – Default Domain |
|
Type |
Fluid |
Location |
B22 |
Materials |
|
Air at 25 C | |
Fluid Definition |
Material Library |
Morphology |
Continuous Fluid |
Settings |
|
Buoyancy Model |
Non Buoyant |
Domain Motion |
Stationary |
Reference Pressure |
1.0000e+00 [atm] |
Heat Transfer Model |
Isothermal |
Fluid Temperature |
2.5000e+01 [C] |
Turbulence Model |
SST |
Turbulent Wall Functions |
Automatic |
Domain |
Boundaries |
|
Default Domain |
Boundary – inlet |
|
Type |
INLET |
|
Location |
inlet |
|
Settings |
||
Flow Regime |
Subsonic |
|
Mass And Momentum |
Cartesian Velocity Components |
|
U |
5.0000e+00 [m s^-1] |
|
V |
0.0000e+00 [m s^-1] |
|
W |
0.0000e+00 [m s^-1] |
|
Turbulence |
Medium Intensity and Eddy Viscosity Ratio |
|
Boundary – opening |
||
Type |
OPENING |
|
Location |
opening |
|
Settings |
||
Flow Regime |
Subsonic |
|
Mass And Momentum |
Entrainment |
|
Relative Pressure |
0.0000e+00 [Pa] |
|
Turbulence |
Zero Gradient |
|
Boundary – wall |
||
Type |
SYMMETRY |
|
Location |
wall |
|
Settings |
||
Boundary – Default Domain Default |
||
Type |
WALL |
|
Location |
F26.22, F29.22, F30.22 |
|
Settings |
||
Mass And Momentum |
No Slip Wall |
|
Wall Roughness |
Smooth Wall |
Task (3.4), (3.5)
Fourth, Results:
Boundary layer thickness and near wall spacing calculation
According to the calculated low Reynold number, the flow was classified as a laminar flow. In Laminar flow viscous forces are effective, velocity streamlines are regular and move smoothly all over the airfoil as shown in figure 20.
Boundary layer is laminar as it depend on Reynold number and started to form because of the effect of viscosity.
First, The calculation of boundary layer thickness for laminar all over the airfoil based on laminar flow over a plate equation.
Boundary layer thickness:
For incompressible flow,
Coefficient of friction
Surface shear stress
Second, determination of near wall spacing and boundary layer calculation, by estimating value. As the flow on laminar flow and value mainly effective in case of turbulent flow, we will focuses on the effect of different first layer thickness and the inflation layers all around the airfoil and how that effect the value.
According to ANSYS CFX Solver Modelling Guide, starting with estimating the value of Y+. After that, by using the following formula we can calculate the first layer thickness or the near wall meshing spacing.
And for boundary layer thickness,
The following table 11 shows the effect of the inflation first layer thickness selection in three different meshing trials on the y+ value at maximum layers number 11, 12 and growth rate 1.2. The used first inflation layer thickness is at the second trial equal 0.004mm. Also illustrate at figure 22, the flow of velocity profile starting from the air foil surface passing by the boundary layer till the free stream. The boundary layer start to reduce the velocity gradually until it reach zero velocity at the airfoil surface, the boundary layer thickness can be calculated from the airfoil surface or starting from zero velocity till the velocity reach 99% of the main stream velocity and gives a parabolic velocity profile. Figure 24 shows the velocity vectors.
At first layer thicken=0.001m |
At first layer thickens =0.004m- (used) |
At first layer thickens =0.01m |
|
Min. Value |
3 |
5.5 |
3.56 |
Max. Value |
26 |
88.6 |
182.57 |
Velocity profile (boundary layer velocity profile) |
Figure 21- velocity profile for trial 1
Figure 21- velocity profile for trial 1
Figure 21- velocity profile for trial 1
Figure 21- velocity profile for trial 1 |
Figure 22- velocity profile for trial 2
Figure 22- velocity profile for trial 2
Figure 22- velocity profile for trial 2
Figure 22- velocity profile for trial 2 |
Figure 23- velocity profile for trial 3
Figure 28- Velocity stream vectorFigure 23- velocity profile for trial 3
Figure 29- Velocity stream vector
Figure 30- Y+ contourFigure 31- Velocity stream vectorFigure 23- velocity profile for trial 3
Figure 32- Velocity stream vectorFigure 23- velocity profile for trial 3 |
Table 11- comparison of different first layer thickness and velocity profile
Figure 24- Velocity stream vector
Figure 25, Shows Y+ values contour over the airfoil surface.
Pressure and velocity
Figure 26 and 27 shows the pressure distribution around the airfoil. It shows the max pressure point at the edge of the airfoil with attacking angel equal 0°. Starting from the Max pressure point in x direction, pressure start to decrease reaching the minimum pressure point after that pressure start to raise.
Figure 26- Pressure distribution contour
Figure 27- Pressure distribution graph
Figure 28 and 29 shows the pressure distribution around the airfoil. It shows zero velocity point at the edge of the airfoil with attacking angel equal 0°. Starting from the zero velocity point in x direction velocity start to increase reaching the maximum velocity after that velocity slightly start to decrease.
Figure 28- Velocity distribution contour
Figure 29- Velocity distribution graph
[1] | K. Volkov, “Governing Equations,” Lecture Notes, 2015. |
[2] | S. Demble, “Fluid Mechanics & Thermodynamic Principles,” Lecture Notes, 2015. |
[3] | S. Dembele, “Turbulance Modelling,” Lecture Notes, 2015. |
[4] | A. Heidari, “Domain Meshing,” Lecture Notes, 2015. |
[5] | B. Massey, Mechanics of Fluids, 8th ed., LONDON AND NEW YORK: Taylor & Francis, 2006. |
[6] | H.Versteeg and W. Malalasekera, An Introduction to Computational Fluid Dynamics, 2nd Ed., Prentice Hall, 2007. |
[7] | ANSYS, “Tetradedral Meshing with Inflation . Introduction to ANSYS Meshing,” ANSYS Customer Training Material, 2010. |
[8] | ANSYS, “ANSYS CFX-Solver Modeling Guide,” 2015-Release 16.2. |
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