For an aircraft to obtain a type design certification, it must 
be demonstrated that it can sustain safe flight into known or 
inadvertent icing conditions. The icing certification process 
involves CFD (Computational Fluid Dynamics) analyses, wind and 
icing tunnel testing (EFD: Experimental Fluid Dynamics), all 
considered “simulation”, and final demonstration of compliance 
through Flight Testing in Natural Icing (FFD: Flight Fluid 
Dynamics). 

Modern CFD-Icing methods, working as a direct extension of 
CFD-Aero technologies, have become an indispensable, if not a 
primary tool, in the certification process. One is referred to 
the just published “Handbook of Numerical Simulation of In-
Flight Icing” (see last page) to note the feverish development 
of new approaches to the simulation of icing over a wide 
variety of flying objects. They are complementing and/or 
replacing 2D methods (airfoils don’t fly; aircraft do), as 
they analyze the aircraft (fuselage, wing, engines, nacelles, 
cockpit windows, sensors, probes, etc.) as an interconnected 
system and not as an assemblage of isolated components. 

The judicial mixing of 2D and 3D CFD-EFD simulation tools 
provides a cost-effective aid-to-design-and-to-certification 
when made part of a well-structured compliance plan. CbA 
(Certification-by-Analysis) is a current “hot” subject, and 
this course puts it into real practice, providing efficient 
tools and showing examples of capabilities and limitations.

The course will highlight how modern icing codes are 
“predictive” as they are based on highly validated physical 
models. Just as one example of where 3D is needed, critical 
ice shapes’ identification and related aerodynamic penalties 
based on 2D airfoil calculations may be inaccurate if not 
altogether misleading as wings have sweep, twist, spanwise 
flows, propeller and engine effects, vortex generators, etc. 
that greatly affect/modify/delay stall and its propagation.
 
The inclusion of icing requirements at the aerodynamic design 
stage allows a more comprehensive exploration of the combined 
aerodynamics/icing envelopes, optimized IPS design, and 
focus/reduce wind tunnels/icing tunnels/flight tests. This 
leads to faster designs, faster testing, faster and more 
complete natural icing campaign, resulting in a safer aircraft 
that is easier to certificate and that remains problem-free 
during its lifecycle.