accomplished on that basically so you feed the shape of the the solid to the to the system and again using fluid dynamics computation to generate data you train it to produce the properties of that shape for example its drag or lift if you are interested in designing air foils for for you know blades of propellers or airplanes or hydrofoils or whatever and then what you have now is on your net that predicts those properties and so because it's on your own that is differentiable so now you can optimize the shape by doing gradient