Main results
- It has been shown that, within the
framework of a local interaction model, the drag of
bodies with the given base area has the lower bound D*, which
is attained by bodies formed by combinations of surface
parts, whose normal makes a constant optimum angle with
the direction of motion. The velocity and medium
characteristics in terms of constants of the drag law
determine this angle independently of the base area.
- For any specified limitations on the
body size, a method of optimum shape design, based on
combining the surface parts of the optimum cone and
planes tangent to it, has been proposed. In particular,
this method allows one to construct optimum starbodies,
optimum asymmetrical and nonconical bodies like missiles
and optimum bodies with a circular base (see Figures below).
- It has been shown that all bodies
constructed have the same total drag D*, minimal for the
given base area and independent of the body length, and
that, even for asymmetrical bodies, the acting force has
no component in a plane perpendicular to the direction of
motion.
- To verify the benefits of the proposed
design, the optimum drag characteristics, found in
Newtonian flow, have been compared with the drag of other
shapes of equivalent length and base area. The results
show that, in most cases, the proposed shapes are more
effective in providing drag reduction than bodies found
in earlier studies (see reference [4] in
Selected Publications).
- Also within the framework of a local
interaction model a solution of the problem of
constructing three-dimensional bodies of maximum
penetration depth has been found. It has been proved that
the desired shapes ( as well as minimal drag bodies) are
formed by combination of the surface parts whose normal
makes a constant optimum angle
with the direction of the motion. In general case this
optimal angle differs from the optimal angle found for
minimal drag bodies. Hence, the method of optimum shape
design, proposed for minimal drag bodies, can be used to
construct the body providing the maximum penetration
depth .
- It has been shown that, for the given
base area all bodies constructed have the same total drag
and the same penetration depth during their rectilinear
motion, but they have different dynamics characteristics
when the rectilinear motion is disturbed. The stability
criterion of the optimum pyramidal body motion has been
found.
- Simulation of 3D-motion of the optimum
shapes is in a good accordance with theoretical
estimations.
