Final answer:
If the pressure in the wake is equal to the static atmospheric pressure, the likely consequence is separation of the airflow (option C).
Step-by-step explanation:
When the pressure in the wake is equal to the static atmospheric pressure, it indicates that the airflow has separated from the surface (option C). In aerodynamics, this separation of airflow is known as flow separation. Flow separation occurs when the air moving over an object, such as an aircraft wing or any aerodynamic surface, detaches from the surface due to adverse pressure gradients.
This separation of airflow leads to a disruption in the smooth flow pattern, causing turbulent vortices in the wake. The separation of airflow is often undesirable in aerodynamics as it can result in reduced lift and increased drag, affecting the overall performance and efficiency of the object.
The other options, such as the expansion of the wake area, decrease in wake turbulence, and formation of a vacuum, are not typically associated with the specific consequence of airflow separation. Understanding the aerodynamic principles related to flow separation is crucial for designing efficient and effective aerospace systems.