getting negative static pressure on airfoil surface
 

hello all!
i am doing a simulation in ansys fluent on flow over an airfoil at transonic speed. i got very good Cl , Cd and Cp distribution. but i'm getting negative static pressure when i'm monitoring surface points on the foil. also my static pressure contour shows negative area...

i've set the operating pressure = 101325 Pa
in B.C, gauge pressure = 0 Pa

i cannot detect the fault....as i went through some tutorials and followed them..... would you please say me how to encounter this problem of negative static pressure ?

thanks and regards.

it simply shows that velocity is increasing

hello far
how can pressure be negative on airfoil surface ? shouldn't it be of some positive value ?

You are correct.

Absolute pressure = atmospheric pressure + gauge pressure

Results you are getting are in terms of gauge pressure, just add atmospheric pressure to get some positive value

thank you sir... but can you clarify me one more thing please ? in ansys tutorial : fluent_13.0_workshop02-airfoil.pdf , they set
# the operating pressure = 0 Pa
# Pressure (gauge) at Boundary condition, P = 71150.4 which they obtained from Po/P relation.

and in my simulation i set # operating pressure = 101325 Pa
and boundary condition # gauge P = 0 Pa
when i tried that of ansys tutorial i got positive pressure but my set up produces negative one... would u explain this please ? i need to know which one is correct ?

thank you for your time.
regards