Dear Agnese, Sorry for the long delay in answering this question. The issue is that in fact it is possible (and used to be a supported but rarely used feature). The challenge, however, is how to make it relatively easy in the context of the current setup for a variety of applications. Nek supports a different gather-scatter handle for each field (velocity, temperature, passive scalar, etc.) We have a handle that allows the user access to the connectivity list, which would give you an opportunity to "disconnect" the periodic faces for the temperature array. I'll try to code up an example for the case of channel flow with a mesh generated by genbox and post it shortly. Incidentally, an alternative approach that we often use for more complex domains would be to use a recycling boundary condition. I think it would not be as efficient, however, as periodicity for the case that you propose. Once again, apologies for the delayed response. Paul ________________________________ From: [email protected] [[email protected]] on behalf of [email protected] [[email protected]] Sent: Thursday, December 22, 2016 4:38 AM To: [email protected] Subject: [Nek5000-users] double mesh ? Hi i am quite new, so i’m sorry if i’m getting things wrong. I am trying to simulate a turbulent channel flow, with a passive scalar. in the streamwise direction, i would like to impose periodic boundary conditions for the flow, and non-periodic for the scalar. in fact the scalar has a point source near the inlet, and i want to see how that develops downstream. as far as i understand this is not supported by nek5000, because the last mesh point is identified with the first mesh point when periodic BC are imposed. correct ? my question is : could i define two meshes, one for the scalar and one for the velocity ? thanks a lot for your help !!! agnese Agnese Seminara -------------------------------- CNRS Laboratoire de physique de la matière condensée Parc Valrose avenue J Vallot 06108 Nice, France +33 (0) 492 076 775 http://sites.unice.fr/site/aseminara/