Hi YiLin,

The spatial derivative in Nektar++ is calculated using the Lagrange polynomial on quadrature points. You can refer to section 2.4.2 of this book
Karniadakis G.E., Sherwin S.J. (2005). Spectral/hp element methods for computational fluid dynamics. Oxford University Press.

Cheers
Ankang

From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Paul Liu <liuyilin.liu@gmail.com>
Sent: 17 February 2022 17:32
To: nektar-users <nektar-users@imperial.ac.uk>
Subject: [Nektar-users] Acoustic Solver Question
 

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Hi Everyone, 

One thing I am noticing with NEKTAR++ is that you specify the base flow function in the configuration/xml file. However, both LEE and APE equations require the estimation of the spatial gradients of the base flow. I was wondering what method of approximation is used within NEKTAR++ as the configuration files does not ask for an analytical expression of the spatial gradients. 

Thank you so much 

YiLin Liu 
403-397-3457
liuyilin.liu@gmail.com
MASc Student at CML UBC