Red Bull’s RB19 finally broke cover at the Bahrain tests last week and, aside from the fact that it proved to be the fastest car there, the most remarkable thing about it was its very close similarity to last year’s title-winning RB18.

    The floor edges – and likely the whole underfloor – have been changed in response to the regulation raising of the rear floor edge by 15mm and that of the diffuser throat by 10mm.

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    The sidepods have had a very subtle reworking – and in a way which suggests some of the radiator area may have been relocated slightly higher up in order to create a wider undercut channel.

    With the underfloor in theory delivering less downforce because of the regulation change (introduced as an anti-porpoising measure), the optimum trade-off of how much of the airflow’s mass goes down the lower bodywork sides and how much through the underfloor will have changed.

    There is a finite volume of air for the aerodynamicists to work with and it must all be directed where it can have the maximum effect.

    The deeper undercut channel can be seen in the comparison with the RB19 (left) and RB18 (right), as can the more intricate floor edges, creating more vortices to compensate for the regulation-raised rear floor edges

    Because the airflow travelling down the side of the car is directed to the space between the rear wheels, it has a direct effect on how hard the airflow exiting the underfloor through the diffusers is working. It creates a pressure differential between the two flows which induces the airflow exiting the underfloor to do so faster.

    The faster that underfloor airflow can be induced to move, the more downforce the floor will create. If there is insufficient volume, it can stall.

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    The balancing of the two flows is therefore crucial, not only at the low ride heights it will see at high speed but also at the higher ride heights of low-speed corners and in the various states of roll, pitch and dive the car will be in throughout the lap.

    We can see that the front upper section of the sidepod has been subtly reworked, rising slightly higher at the back of the cockpit, suggesting some relocated radiator surfaces there. This has apparently created the space beneath to create a bigger undercut, which will increase the airflow capacity travelling down the sides of the car.

    To create the additional undercut, the upper surface of the sidepod has been refashioned, with the RB19’s bodywork (shown above) raised towards the rear of the cockpit compared to that of the RB18 (shown below)

    The section of bodywork forming the ‘roof’ of the undercut has been given an enhanced lip, thereby more clearly separating out the flow travelling down the upper surface of the sidepod with that travelling along the channel created by the undercut.

    The less these interfere with each other, the greater energy the airflow will contain when they eventually merge as they are directed between the rear wheels.

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    Red Bull last year showed a mastery of the underfloor dynamics so crucial in a ground effect car with a design visibly more sophisticated than that of Ferrari or Mercedes.

    The small external changes made to the latest car suggest that its understanding was at a very high level at its first attempt. On the evidence of Bahrain testing, the rest still appear to be trying to catch up.

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