******************* 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. ******************* Dear all I want to solve a two-phase flow with Nektar++. The governing equations lead to div(viscosity(grad) - factor)u=RHS that should solve with Helmholtz solver in the velocity correction scheme. As the flow is two-phase the viscosity varied across the domain. To solve the above equation, I set eVarCoeff D00=D11=D22=viscosity, but it doesn't work. Would you say how can I set the above equation in helmsolve? best regards, Rouhanian