Cfd modelling of h-darrieus vertical axis wind turbine

4.5 SOLVER SETTINGS- FLUENT SETUP 
The simulation setup must be completed after the meshing procedure is completed. It may be 
sufficient to discuss the approach used to solve the unsteady flow around the VAWT before going 
into how the different simulation settings were established. In reality, a variety of strategies can be 
utilized to simulate this erratic flow. [79]. 
A sliding mesh approach was utilized to model the turbine's rotation.[80]. A portion of the mesh 
changes with time according to the rotational velocity required in each simulation in this type of 
simulation. As a result, in Fluent, a transient simulation is utilized to rotate the mesh, with a time 
step set. The rotating and fixed domains are linked by an interface, which assures that the flow 
properties of cells in different domains are transferred accurately. 
4.5.1 The Sliding Mesh Approach 
When calculating an unsteady flow field, the Sliding Mesh approach should be utilized if a time-
accurate solution is needed. It's the most precise way for simulating flows in moving reference 
frames, but it's also the most time-consuming. 
This method employs two or more cell zones, each of which is separated from the opposing cell 
zone by at least one 'interface zone.' A grid interface is formed by connecting the interface zones of 
adjacent cell zones, and the two cell zones will move relative to each other along the grid interface. 
[80] 

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In this study, the interfaces required for our modelling have already been created, and so this process 
is explained later. 
4.6 SOLUTION SETUP 
This part covers the setting and setup of the Fluent application used in this thesis' simulations, as 
well as the numerical solver and turbulence model choices, among other aspects. 
As a solver, a pressure-based option is used. When dealing with incompressible flows, the Fluent 
user guide suggests it. [81]. At the same time, due to the flow's unpredictability, a time-dependent 
solution is necessary. [82]. As a result, depending on the time step value, the rotating mesh moves in 
discrete steps relative to the stationary mesh during the calculation.