Hello,

i'm trying to perform some accuracy tests of the NITA - FRACTIONAL STEP time integration scheme employed in Fluent using the Taylor Test Case, which is a double periodic array of vortex whose kinetic energy is decaying in time.

I performed several simulations with several grids, domains, boundary conditions, pressure interpolation schemes and space discretizations but i have misleading results.

Using exactly the same conditions cited in the paper

Sung-Eun Kim Boris Makarov

An Implicit Fractional-Step Method for Efficient Transient Simulation of Incompressible Flows

AIAA 2005-5253

Sorry, i pushed the wrong button.

Using the same conditions cited in the paper, i obtain the same results cited there, a 2nd order accurate in time scheme.

But, just going outside the conditions cited there, i always obtain only a first order time accurate scheme.

So i'd like to know if someone has experience in this or even know if there are some other papers where the scheme has been more rigorously tested and with which compare my results.

Thanks a lot, any help is appreciated