Abstract:
Present work carries out numerical investigations for 3-D
model of flapping bird wing (owl) by use of commercial
software ANSYS Fluent 15.0. In past, mostly standard air foil
has been used to study flow characteristics of flapping motion.
In the present study, geometry selection of owl wing has been
done based on similar research reported in literature.
Computations are carried out to simulate lift and drag
characteristics of owl wing for different parameters, such as
Reynolds number, angle of attack, frequency and amplitude. In
the computational domain, dynamic meshing has been used to
impart motion to the wing with the help of User Defined
Function. Spring based smoothing function is selected for
smoothing during dynamic motion of the wing. Literature
reports that propulsive power can be generated by the flapping
motion of wing beyond certain value of flapping frequency.
Flapping motion in 3-D can be considered as a combination of
both rotational and translational motions. For simplicity, the
rotational motions are assumed to be present only about two
axes, namely about stream-wise and span-wise directions.
Effect of phase difference between the two rotational motions
has been investigated and presented in the form of force
coefficient ratio (R), which is the ratio of mean lift coefficient
to mean drag coefficient. Critical value of Reynolds number has
been computed at which the value of ratio R becomes equal to
unity. Results show that an increase in flapping frequency is
associated with a decrease in the value of mean drag
coefficient.
Description:
Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .
