8/19/2019 Airfoil CFD Instructions

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Fig. 1 Computational domain

Fig. 2(a) Grid used in domain without slotFig. 2(b) Zoomed view of meshed domain

In this research a body fitted C-type multi-block structured grid was used for airfoil

Skewness of the mesh was corrected up to maximum equi-sied skewness of !"#$$ in such a

way that %&' of the total elements have less than !"& skewness("

Table 1: Grid Independency )est

Boundary Conditions: )he boundary conditions must be carefully specified to obtain

meaningful solutions* and their implementation is usually based on physics" +ll the boundary

condition can be seen in ,ig" " ,reestream velocity .$/&" m0s( is specified at the inlet of the

computational domain* whereas* atmospheric pressure is specified at the outlet of the domain"

+irfoil

Grid Type 1ithout slot 1ith slotNo. of Cells   C L/C  No. of Cells   C L/C 

1 23#! "!3 2/42/ /"#2

2 &$!4 "43# &/2/ #"$!&

! #&!!! "2%$ #3$4! #"4&2

" $$&%3 "2% $44$4! #"4&

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5n the airfoil surface* no-slip conditions are applied" )he outer boundary is usually placed far 

from the airfoil surface* at least six chords away" 5ne common boundary condition at outlet is

that where instability waves emitted from the body are free to pass and are not reflected back"

In this study* a non-reflecting boundary condition is used at the outer boundary as pressure

outlet"

CF #ol$er #ettings: ,inite volume based density solver is used for computing velocity and

 pressures at different points" Second-order upwind 6iscretiation scheme is used in the study"

7eynolds number .7e( based on chord length .C ( is calculated as $"#8$!/ which corresponds

to an upstream velocity of $/&" m0s" Suitable under-relaxation factors are set for pressure*

density* body forces and momentum in the code" 9-plus .9:( value for all the case is taken

less than $ to capture separation phenomena accurately" +ll the simulations are carried out in

the steady-state mode" )he steady-state simulations are performed for a sufficient number of

iterations until the flow data are converged to a constant solution"

Turbulen%e &odels: shear-stress transport .SS)( k- ω turbulence model .;enter* $%%( is

used"