The spatial discretization of each term in a given equation is carried out in the TRUST platform by what we call the operators (operators for convective terms, diffusion, gradient, divergence, ...) It is important to keep in mind that all these operators are dependent of the employed discretization; in particular on the variables localisation.

In what follows, the available convective operator schemes are summarized.

Attention: The diffusion term is more or less a Laplacien operator and is thus always discretized by a centered difference scheme.

Attention: TRUST allows the user to neglect the operator contribution. This can be done by using the keyword negligeable in the convection and/or diffusion block.

Finite Volume Difference (VDF) Schemes

Scheme	Keyword	Description
Upwind scheme	Amont	Corresponds to first order upwind scheme.
Centered scheme	Centre or Centre4	They correspond respectively to a second and fourth order centered schemes.
QUICK scheme	Quick	This is the third order Quadratic Upstream Interpolation for Convective Kinematics (Quick) scheme.

Finite Element Volume (VEF) Schemes

Scheme	Keyword	Description
Upwind scheme	Amont	Corresponds to first order upwind scheme.
Centered scheme	Centre or KCentre	Corresponds to second order centered scheme.
QUICK scheme	KQuick	This is the third order Quadratic Upstream Interpolation for Convective Kinematics (Quick) scheme.
EF-Stab scheme	EF_Stab	This scheme is an upwind/centered mixed schemes. The behavior is controlled by a parameter, alpha, where the scheme behaves as a pure upwind with alpha = 1 and centered with alpha = 0.
MUSCL scheme	Muscl	This is the second order Monotonic Upstream-centered Scheme for Conservation Laws (MUSCL) scheme.

PolyMAC-series Schemes

Scheme	Keyword	Description
Upwind scheme	Amont	Corresponds to first order upwind scheme.
Centered scheme	Centre	Corresponds to second order centered scheme.
EF-Stab scheme	EF_Stab	This scheme is an upwind/centered mixed schemes. The behavior is controlled by a parameter, alpha, where the scheme behaves as a pure upwind with alpha = 1 and centered with alpha = 0.