Mechanics of Fibrous Materials

Mixture Theories

Resistive Force ¨C body drag

• Little is known about the magnitude of the wave drag relative to the other drag components

• Balance between skin friction and head resistance depends upon Reynolds number (NR=¦Ñva/¦Ç)

• NR < 2000 Skin friction dominant

• NR > 2000 Head resistance dominant

Resistive Force ¨C Human being

• NR >> 2000 head resistance dominant

• Experimental confirmed this theoretical prediction.

• Decrease skin friction contribute relatively small to the reduction of resistive drag force.

Mechanism of SPEEDO Fastskin

• Mimics the sharkskin with drag-reducing grooves.

• Reduce drag by channeling the water along grooves in the fabric.

• These grooves allow the water to spiral in microscopic vortices.

• Fastskin passive drag values were significantly less than normal swimsuits.