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### 9.2. List of the low-Re models available in PHOENICS

PHOENICS makes provision for the following low-Reynolds-number
turbulence models:

- the Lam-Bremhorst low-Re extension to the KE-EP model;
- the two-layer low-Re KE-EP model;
- the Wilcox low-Re extension to the KE-OMEG model;
- the Van-Driest low-Re damping model for the length scale; and
- an algebraic eddy viscosity model based on the solution of a
generalised turbulent-length-scale variable LTLS and Spalding's

In addition, two options are provided for the turbulent viscosity to
be modified by multiplication by a factor which is a function of
the local Reynolds number of turbulence.
This feature, here called LRNM (standing for Local Reynolds Number
Modification), is provided in subroutine GXENUT, where it is
activated by setting IENUTA = 6 or 9.

The LRNM turbulent-viscosity formula for INEUTA=6 is:

vist = vist_nom * amin1(1.0 , (A * vist_nom/visl) ** B)

**
where: (vist_nom/visl) is the Local Reynolds Number (LRN)
vist = turbulent kinematic viscosity to be used
vist_nom = nominal (high-Reynolds-number) value of vist
visl = laminar viscosity
A = ENUTA
B = ENUTB
**

Suitable values for A and B may be 0.05 and 4.0.
The LRNM turbulent-viscosity formula for INEUTA=9 is:

vist = vist_nom for ENUTA * LRN < 1.0, and
vist = 0.0 for ENUTA * LRN < 1.0

A suitable value for ENUTA may be 0.05 .

Relevant "help-file" entries are :- DISWAL, EL1, EL1A, EL2, EL2A,
ENUT, ENUTA, GENK, PRT, TURBUL, TURMOD.

Relevant "Encyclopaedia" entries include: CHEN-Kim KE-EP turbulence
model, K-Omega turbulence model, LAM-Bremhorst KE-EP turbulence
model, LVEL turbulence model, RNG KE-EP turbulence model, TWO-Layer
KE-EP turbulence model, VAN-Driest damping model.

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