Bill Bulat
Ansys Employee

Hi Helen,

Quadratic elements have midside nodes, linear elements do not. When quadratic elements become severely distorted, sometimes the displaced location(s) of the midside nodes introduce sharp bends in the element edges on which they reside, or they may pass through the domain of the element and penetrate a face on the opposite side of that element. A linear mesh is often less susceptible to "mesh entanglement" than a quadratic one because linear elements do not have the midside nodes that are at times responsible for excessive element distortion.

Kind regards,