Found This Helpful. Comstock/Comstock/Getty Images. Temperature can affect both the structure of a molecule and how it interacts with surrounding molecules. Heating some molecules, particularly large, biological molecules such as proteins or nucleic acids, will cause them to change shape or even to break up.
The air comes through the diffusers in much larger velocities and different temperatures than the ones tolerated in the space. Due to diffusion, the velocity and the temperature differences are gradually decreased until they reach the tolerable limits.
In terms of beneficial downforce versus parasitic drag, a diffuser is vastly superior to any freestanding wing. The diffuser acts as an expansion chamber to manage the air as it exits from underneath the car and reintegrates it with higher-pressure ambient air. Smoothing this transition reduces turbulence and drag in the car's wake and improves airflow under the car.