CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   FLUENT (https://www.cfd-online.com/Forums/fluent/)
-   -   static temperature more than total temperature ?? (https://www.cfd-online.com/Forums/fluent/31818-static-temperature-more-than-total-temperature.html)

 mahesh July 14, 2003 05:12

static temperature more than total temperature ??

Hi All,

We are getting static temperature more than total temperature ? has anybody came across such a situation ? why it happens ? we think physically it is not correct..

Mahesh

 Mcgregor July 15, 2003 09:03

Re: static temperature more than total temperature

Hi there,

If you are annalysing the temperature in a flowing fluid, then i think this is the result you should expect as total temperature includes viscous heating effects. The two should only be slightly different though (no major differences)

Mcgregor

 gelislim July 17, 2003 09:10

Re: static temperature more than total temperature

Hi mahesh,

Static temperature is the temperature of your fluid. That means when you use a temp. sensor you read the static temperature. On the other hand, total temperature (stagnation temperature)is the temperature your fluid has when it is decelerated to zero velocity isentropically and its kinetic energy is changed into internal energy.

q : Is there any difference between their values ?

a : yes, especialy in high speed flows. The higher the mach number of your flow the bigger the difference

 rogbrito June 21, 2009 17:08

I´m simulating on a solid only domain and my results show that the static temperatures have greater results than the total temperatures, for a transient simulation. Why of this? I used the ANSYS Fluent 12 software. When i use ANSYS CFX 12, there is no option to export, in ANSYS CFX Pre, the total temperature results. How to export the total temperature to ANSYS CFX Post 12?

LIBRARY:
MATERIAL: Amostrak10Sol
Material Group = CHT Solids,Particle Solids
Option = Pure Substance
Thermodynamic State = Solid
PROPERTIES:
Option = General Material
EQUATION OF STATE:
Density = 14900 [kg m^-3]
Molar Mass = 1.0 [kg kmol^-1]
Option = Value
END
SPECIFIC HEAT CAPACITY:
Option = Value
Specific Heat Capacity = 508.1237 [J kg^-1 K^-1]
END
THERMAL CONDUCTIVITY:
Option = Value
Thermal Conductivity = 73 [W m^-1 K^-1]
END
END
END
END
FLOW: Flow Analysis 1
SOLUTION UNITS:
Angle Units = [rad]
Length Units = [m]
Mass Units = [kg]
Solid Angle Units = [sr]
Temperature Units = [K]
Time Units = [s]
END
ANALYSIS TYPE:
Option = Transient
EXTERNAL SOLVER COUPLING:
Option = None
END
INITIAL TIME:
Option = Automatic with Value
Time = 0 [s]
END
TIME DURATION:
Option = Total Time
Total Time = 110.778 [s]
END
TIME STEPS:
Option = Timesteps
Timesteps = 0.222 [s]
END
END
DOMAIN: Default Domain
Coord Frame = Coord 0
Domain Type = Solid
Location = ASM.1 METAL
BOUNDARY: Conveccaoo
Boundary Type = WALL
Location = ASM.1 CONVECCAOTOTAL
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Heat Transfer Coefficient = 20 [W m^-2 K^-1]
Option = Heat Transfer Coefficient
Outside Temperature = 29.34 [C]
END
END
END
BOUNDARY: Fluxoo
Boundary Type = WALL
Location = SOL_2D_REGION
BOUNDARY CONDITIONS:
HEAT TRANSFER:
Heat Flux in = 1 [W m^-2]
Option = Heat Flux
END
END
END
DOMAIN MODELS:
DOMAIN MOTION:
Option = Stationary
END
MESH DEFORMATION:
Option = None
END
END
INITIALISATION:
Option = Automatic
INITIAL CONDITIONS:
TEMPERATURE:
Option = Automatic with Value
Temperature = 0 [C]
END
END
END
SOLID DEFINITION: Solid 1
Material = Amostrak10Sol
Option = Material Library
MORPHOLOGY:
Option = Continuous Solid
END
END
SOLID MODELS:
HEAT TRANSFER MODEL:
Option = Thermal Energy
END
Option = None
END
END
END
OUTPUT CONTROL:
MONITOR OBJECTS:
MONITOR BALANCES:
Option = Full
END
MONITOR FORCES:
Option = Full
END
MONITOR PARTICLES:
Option = Full
END
MONITOR POINT: T4
Cartesian Coordinates = 4.3 [mm], 3.5 [mm], 4.7 [mm]
Option = Cartesian Coordinates
Output Variables List = Temperature
END
MONITOR RESIDUALS:
Option = Full
END
MONITOR TOTALS:
Option = Full
END
END
RESULTS:
File Compression Level = Default
Include Mesh = On
Option = Selected Variables
Output Variables List = Temperature
END
TRANSIENT RESULTS: Transient Results 1
File Compression Level = Default
Include Mesh = On
Option = Selected Variables
Output Variables List = Temperature
OUTPUT FREQUENCY:
Option = Time Interval
Time Interval = 0.222 [s]
END
END
END
SOLVER CONTROL:
Option = High Resolution
END
CONVERGENCE CONTROL:
Maximum Number of Coefficient Loops = 500
Minimum Number of Coefficient Loops = 1
Timescale Control = Coefficient Loops
END
CONVERGENCE CRITERIA:
Residual Target = 0.000001
Residual Type = RMS
END
TRANSIENT SCHEME:
Option = Second Order Backward Euler
TIMESTEP INITIALISATION:
Option = Automatic
END
END
END
END
COMMAND FILE:
Version = 12.0.1
Results Version = 12.0
END
SIMULATION CONTROL:
EXECUTION CONTROL:
EXECUTABLE SELECTION:
Double Precision = On
END
INTERPOLATOR STEP CONTROL:
Runtime Priority = Standard
MEMORY CONTROL:
Memory Allocation Factor = 1.0
END
END
PARALLEL HOST LIBRARY:
HOST DEFINITION: unifei
Host Architecture String = winnt-amd64
Installation Root = C:\Program Files\ANSYS Inc\v%v\CFX
END
END
PARTITIONER STEP CONTROL:
Multidomain Option = Independent Partitioning
Runtime Priority = Standard
EXECUTABLE SELECTION:
Use Large Problem Partitioner = Off
END
MEMORY CONTROL:
Memory Allocation Factor = 1.0
END
PARTITIONING TYPE:
MeTiS Type = k-way
Option = MeTiS
Partition Size Rule = Automatic
Partition Weight Factors = 0.250, 0.250, 0.250, 0.250
END
END
RUN DEFINITION:
Run Mode = Full
Solver Input File = \
C:\0_CIBIM_Validacao_18_Junho_2009_cedo\Caso_Teste _CIBIM\CasoValidaca\
oCIBIM.def
END
SOLVER STEP CONTROL:
Runtime Priority = High
MEMORY CONTROL:
Memory Allocation Factor = 1.0
END
PARALLEL ENVIRONMENT:
Number of Processes = 4
Start Method = HP MPI Local Parallel
Parallel Host List = unifei*4
END
END
END
END

 marcel_jay May 18, 2016 06:09

Well old Thread but since there is no clear answer I checked something in my CFX-Simulation:

The Total Temperature seems to be only valid for the fluid domain, hence, the max. value in this domain is higher than the static "temperature" variable.
In the solid domain though, the total temperature doesn't exist which is why the "temperature" can be higher. Assuming the heat source is in the solid.

 All times are GMT -4. The time now is 03:08.