******************* This email originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping for this address. ******************* Hello Nektar++ Community, I am using the HOutflow condition at the outlet of my flow domain with the incompressible Navier-Stokes solver. According to the user guide, this is enforcing a boundary condition defined by Dong, Karniadakis and Chryssostomidis in equation 3 of their paper: A robust and accurate outflow boundary condition for incompressible flow simulations on severely-truncated unbounded domains. This boundary condition is also stated in equations 11.27 and 11.28 of the user guide. Both the paper and the user guide state that δ is "chosen to be sufficiently small" without explaining what constitutes sufficiently small. Would anyone happen to know what value of δ is used by Nektar++ or where I could find it? Kind regards, Isaac