This is absolutely true - one element corresponds to a spectral calculation. You do need, however, enough points to resolve the scales of motion, as is always the case, which means you need large values of N. (The first spectral results were 32^3, and then the breakthrough 100^3 by Orszag in the early 70s - the famed centicubed simulations.) Paul ________________________________________ From: [email protected] [[email protected]] on behalf of [email protected] [[email protected]] Sent: Tuesday, August 02, 2016 10:53 AM To: [email protected] Subject: [Nek5000-users] Spectral method with Nek All, I was wondering if the following statement is true or false: "If a single element is used for the whole domain then one can claim the Nek simulation is spectral instead of spectral element". Based on this, I carried out DNS on cavity for relatively large Reynolds numbers and I was not able to capture the instability mechanisms with one element (even when I increased the power of polynomial to 12 or 18). While I'm not surprised, I just wanted to see if anyone else has a similar experience. As a side question, why Nek utilizes Legendre polynomials instead of Chebyshev for each element? Is this because we're also interested in modeling non-uniformly spaced nodes? Best, Saleh _______________________________________________ Nek5000-users mailing list [email protected] https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users