3d Water and Jet flow in flume

MOHID Water forum. Questions and discussion around MOHID Water
k.steenhauer@abdn.ac.uk
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Posts: 3
Joined: Thu Jan 01, 1970 00:00

3d Water and Jet flow in flume

Postby k.steenhauer@abdn.ac.uk » Wed Apr 28, 2010 15:56

Hi,

The main aim is to simulate an imaginary set up, that consists of a 20m long, 1m wide and 1m high (free surface) flume with a particular bed topography and with a for now uniform velocity profile at the inflow boundary and a high salinity (jet-like) flow near the inflow boundary. The free surface water level in the flume stays constant with a water depth of 1m. I am new to this, so I am afraid I have many questions.

I created a grid.dat file generated by
Mohid Digital Terrain Creator. I tried to run a simple Mohid water case without turbulence and lagrangian modules). However, it keeps generating a 'new bathymetry' file and tells me to
modify the Nomfich.dat file and then re-run the model. I do this, but then the same happens again. I cannot seem to get passed this error.

I don't understand the geometry module with regard to the amount of layers in the vertical. I want a very detailed picture of the dispersion of the high salinity flow, does that mean I have to increase my amount of layers in the vertical? So for instance divinding the 1m water depth that I have in 100 or more layers with a equidistant of 0.01m?
This is my geometry file (Note I have highlighted questions in the comments behind the parameters)!:

!FACES_OPTION : 1 !don'tunderstand rthis parameter
IMPERMEABILITY : 0
<begindomain>
ID : 1
TYPE : CARTESIAN
LAYERS : 100
EQUIDISTANT : 0.01
!LAYERTHICKNESS : 0.2 0.2 0.2 0.2 0.2 ! Is this needed when parameter EQUIDISTANT is set?
!TOLERANCEDEPTH : 0.05
DOMAINDEPTH : -99.0
!MININITIALLAYERTHICKNESS : 0.05
<enddomain>

Further, if I want to have a uniform velocity boundary of 1m/s coming into the flume (inflow boundary), what do I need to tell the hydrodynamic file. Is it just the following parameters (Note I have highlighted questions in the comments behind the parameters)!:
INITIAL_ELEVATION : 1
INITIAL_ELEVATION_VALUE : 1 !iam not sure about this I think this is water level in m?;
INITIAL_VEL_U : 1.0 ! m/s?
INITIAL_VEL_V : 0.0

How does MOHID water work out the outflow boundary?

Further I want to include the following turbulence module, but do I need to use GOTM and if so how does it work? This is my turbulence file that I would like to include
MODVISH : smagorinsky
MODTURB : turbulence_equation !kappa epsilon
CONTINUOUS : 0
MLD : 1 !compute themixed layer length
MLD_BOTTOM : 1 !compute thebottom mixed layer length
TKE_MLD : 1e-5
RICH_MLD : 0.5
TIME_SERIE : 0
OUTPUT_TIME : 0 900.

Further if I want to simulate a continuous high salinity flow with a certain flux coming into the flume near the inflow boundary. The jet-like flow is positioned on the bed surface in a 45 degree angle with the horizontal bed in the middle of the flume directing the flow in streamwise direction. Also the only thing I would like to give as an input property is the density of the ambient flow and the density of the jet. How do I do this?
I use the following lagrangian file (Note I have highlighted questions in the comments behind the parameters)!

<BeginOrigin>
ORIGIN_NAME : Origin 1
OLD : 0
GROUP_ID : 1
EMISSION_SPATIAL : Point
EMISSION_TEMPORAL : Continuous
FLOW : 2.18 ! is this in m/s?
FLOAT : 0
MOVEMENT : SullivanAllen

VARVELHX : 0.20 ! I am not sure what this is, and in what unit?
VARVELH : 0.03 ! I am not sure what this is, and in what unit?

TURB_V : Profile !
POSITION_CELLS : 1 0.5 !Is this the position of the outlet in meters?

DEPTH_CELLS : 1
COMPUTE_PLUME : 1
COMPUTE_BUOYANCY : 1
DENSITY_METHOD : 2
COEF_INITIAL_MIXING : 1
ADVECTION : 1
JET_DATA_FILE : C:\\Documents and Settings\\eng923\\My Documents\\MOHID\\Simulation_1\\data\\jetmohid_1.dat

VOLUME_INCREASE : Double ! Do I need to set this parameter?
VOLFAC : 1e4 ! what does this parameter do?
JET_DT : 300 ! What is this parameter?

<<BeginProperty>>
NAME : temperature
UNITS : ºC
CONCENTRATION : 25.0
TIME_SERIE : 1
<<EndProperty>>

<<BeginProperty>>
NAME : salinity
UNITS : psu
CONCENTRATION : 45
TIME_SERIE : 1
<<EndProperty>>
<EndOrigin>

This is my jet file
POSITION_METERS : 1 0.5 !Is this the position of the outlet in meters?should be the same as lagrangian file, i think?

PORT_DIAMETER : 0.025 ! in m
PORT_BOTTOM_DISTANCE : 0.01 ! outlet distance to the bed in m?
PORT_ANGLE_XY : 0 ! ! iam not sure what angle this is
OUTFALL_ANGLE : 90 ! 90 degrees so does this mean the outlet is parallel to the z-axis?
OUTFALL_LENGTH : 0.01 !Needs to coincide with PORT_BOTTOM_DISTANCE ?

PORT_ANGLE_HZ : 0 ! iam not sure what angle this is
PORTS_NUMBER : 1
RUN_MAX_PERIOD : 3600
DT_OUTPUT : 1
MAX_DV : 1
MAX_DT : 10
PARAMETERIZATION : CORJET ! what does this parameter do
OUTPUT_TYPE : CLOUD ! what does this parameter do

In general are there any more detailed manuals available to the existing MOHIDJET pdf. Are there any examples yet similar to my problem?

Thank you very much for you time.

Regards

Kate

luis_at_mohid.com
MOHID Developer
Posts: 553
Joined: Thu Jan 01, 1970 00:00
Location: Instituto Superior Técnico - Technical University of Lisbon
Contact:

Postby luis_at_mohid.com » Tue Jun 08, 2010 10:23

Hi!

Uff, big post with lots of questions... :-)
I've answered the part of the vertical coordinates in your other post.
Regarding the rest:

1) MOHID always uses I.S. units (i.e. meters, kg, etc)
2) To activate the k-epsilon model in GOTM just define:

MODTURB : turbulence_equation

be careful, if you define in the Turbulence file

MODTURB : turbulence_equation !kappa epsilon


there will be an error, because the model needs to read a string after the keyword MODTURB, so you cannot write anything rather than turbulence_equation. When the keyword value is a string you cannot write any comments in front of it.

3) I'll send you the Lagrangian and Jet user manuals by e-mail

Hope this helps,

Luis

gerry.salamena@my.jcu.edu.au
MOHID Beginner
Posts: 5
Joined: Sun Jun 29, 2014 10:14

Re: 3d Water and Jet flow in flume

Postby gerry.salamena@my.jcu.edu.au » Tue Jan 27, 2015 02:13

Hi Guys,
May I be involved in this discussion?. I am combining lagrangian module with turbulence using GOTM. How to synchronize both? I was running lagrangian module without GOTM and the point moved under the hydrodynamics influence. However, I find ERR004 when GOTM is involved. Do you have any advises that can let both work? I think that might be from GOTM file or Turbulence_x.dat that I need to have a look.

Thanks for your attention and your help will be so meaningful

Best
Gerry


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