## MIX UNTRIM.DAT

### From BAWiki

## Contents

## Basic Information

### File-Type

mix_untrim.dat

### Version

1.0 / November 2007

### Description-Date

December 2010

## Significance of the File

contains general input Data for the package MIX

## File-Contents (in Catchwords)

**Input Steering Data**

- General steering Data (Block
**Turbulence_Model**)

- Key
**"Constant_Viscosity"**: prescribed**constant**turbulent Viscosity and Diffusivity. - Key "
**Zero_Equation_Model"**:**Zero Equation Models**. No need to solve additional equations. (The models differs principaly in the way they compute the mixing length). - Key
**"One_Equation_model"**:**One Equation Models**. One additional equation for the turbulent kinetic energy has to be solved. - Key
**"Two_Equation_model"**:**Two Equation Models**. Two additional equations for the turbulent kinetic energy and the dissipation has to be solved.

- Key
- Remarks on the following optional blocks:
- The user is requested to choose one of the methods listed above.
- Depending on the used method, the corresponding block below has to be filled.
- The last two blocks are optional

- Block
**Zero_Equation_Model**.

- Key
**"Classical_Prandtl"**: the mixing length is computed using the**Prandtl**approach. - Key
**"Nezu_Model"**: the mixing length is computed using the**Nezu and Nakagawa**appraoch. - Key
**"Quetin_Model"**: the mixing length is computed using the**Quetin**approach. - Key
**"Tsanis_Model"**: the mixing length is computed using the**Tsanis**approach.

For the models listed above, a**Damping Function**which depends on the**Richardson Number**is used. Hence, the effect of flow stratification is taken into account (stable or unstable flows). - Key
**"Rodi_Model"**: the turbulent Viscosity is computed using the**Rodi**model. (for the mixing length, the approach after Nezu and Nakagawa is used by Rodi)

The Rodi Model has a proper damping function for tracers which depends on the Richardson number. The damping of momentum is performed by a term that depends on the density gradient. This Term is introduced next to the velocity gradients.. - Key
**"DelftAlg_Model"**: the turbulent Viscosity is computed using an**Algebraic Closure Model**. The friction velocity on the bed and at the free surface are used to derive the turbulent kinetic energy. To close the problem, the mixing length after Nezu and Nakagawa is used. - Key
**"DelftAem_Model"**: this model is a**combination**of DelftAlg_Model and Nezu_Model. The maximum of the two models is taken. In DelfAlg_Model and DelftAem_Model, the turbulent Viscosity damping function after**Busch**is used. For tracers, the**Munk and Anderson**damping function is implemented.

- Key

More informations are available in the document (ca. 120 kB) A Short Theoretical Description of the Mixing Length Models Implemented in the ProgHome Package MIX

- Block
**One_Equation_Model**.

- In the one equation models, an additional equation for the
**TKE**(turbulent kinetic Energy) needs to be solved. The Dissipation term**E**is derived from the KTE and other method specific parameters. Every single model has its own Damping function. Key**"Norris_Reynolds"**: the Dissipation is computed using the**Norris Reynolds**Model. - Key
**"Hassid_Poreh"**: the Dissipation is computed using the**Hassid and Poreh**Model. - Key
**"Wolfstein"**:the Dissipation is computed using the**Wolfstein**Model.

- In the one equation models, an additional equation for the

- Block
**Two_Equation_Model**.

- In the two equation models, the solution of two additional equations for the
**TKE**and the Dissipation**E**is requested. The models are classified according to the Reynolds number. Practically, this is realized through the use of different damping functions.- Key
**"K-E_Low"**: the model**K-E_Low**is appropriated for low Reynolds numbers where the distance to the wall plays an important role. - Key
**"K-E_High"**: the model**K-E_High**is the standard case and is appropriated for high Reynolds numbers.

- Key

- (optional) Block
**Minimum_Visco_Diff.**

**Minimum**default values for Diffusivity and Viscosity are implemented. The user is given the possibility to introduce his own minimum values. Additionally, the mimimum Diffusivity can be computed using the Ozmidov mixing length. The user has to define a weighting parameter between the Ozmidov mixing length and the mixing length of the method.- (optional) Key
**"Minimum_Vis"**: user defined**minimum turbulent Viscosity**. can be zero. - (optional) Key
**"Minimum_Dif"**: user defined**minimum turbulent Diffusivity**. can not be zero. - (optional) Key
**"Ozmidov_Wei"**: user defined**weighting parameter**for Ozmidovs mixing length.

- (optional) Key

- (optional) Block
**Constant_Visco_Diff**.

- For Diffusivity and Viscosity, default
**constant values**are implemented. The user is given the possibility to introduce his proper values.- (optional) Key
**"Constant_Vis"**: user defined**constante turbulent Viscosity.** - (optional) Key
**"Minimum_Dif"**: user defined**constante turbulent Diffusivity**.

- (optional) Key

## Programs using this Type of File

## Additional Information

### Language

Fortran90

### File-Form

FORMATTED

### File-Access

SEQUENTIAL

### File-Extension

.dat

### WRITE-Subroutine(s)/Module(s)

interactive generation (Editor)

### READ-Subroutine(s)/Module(s)

$PROGHOME/fortran/lib/mix/*/mod_m_mix_steer.f90

### Original Version

### Maintenance

### Example-File

siehe $PROGHOME/examples/lib/mix/mix.dat

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