Fluid flow modification apparatus using fractal configurations

A fluid flow modification apparatus comprising:

• a plurality of fluid flow modification elements each having a first surface portion against which a fluid (F) can flow and a second surface portion along which the fluid (F) can flow, said plurality of fluid flow modification elements being arranged in a number of sets, wherein
• a first set of fluid flow modification elements comprises a plurality of fluid flow modification elements with a first surface portion having a first surface area;
• and
• a second set of fluid flow modification elements comprises a plurality of fluid flow modification elements with a first surface portion having a second surface area different to the first surface area,
• the first set of fluid flow modification elements including a first type of fluid flow modification element and a second type of fluid flow modification element, a depth of the second surface portion in the direction of flow of the fluid of the first type of fluid flow modification element being different from a depth of the second surface portion in the direction of flow of the fluid of the second type of fluid flow modification element, wherein a ratio of the depth of the second surface portion of at least one of the fluid flow modification elements in the direction of flow of the fluid (F) to a width of the first surface portion of said fluid flow modification element across the direction of flow of the fluid (F) is within the range 0.1 to 10.