Sentence:  Essentially these birefringence studies show that at low rates of shear a tension is present at 45 ` to the direction of shear , and as the rate of shear increases , the direction of the maximum tension <WSD>moves</WSD> asymptotically toward the direction of shear . 
Meaning of the word marked with <WSD> tags:  change location; move, travel, or proceed, also metaphorically