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fluid flow but temperature raises from nowhere? |
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September 10, 2014, 14:19
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fluid flow but temperature raises from nowhere?
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#1 |
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I have following physics defined for one fluid and one solid:
Code:
| +-3 Physics 1 Regions [all_inside] | | | Interfaces [Interface 1] | | +-1 Models | | | +-1 Constant Density | | | +-2 Gas | | | | `-1 Air Database Material Air (Air) [Standard/Gases] | | | | `-1 Material Properties | | | | +-1 Density Method Constant | | | | | `-1 Constant Value 1.18415 kg/m^3 | | | | +-2 Dynamic Viscosity Method Constant | | | | | `-1 Constant Value 1.85508E-5 Pa-s | | | | +-3 Specific Heat Method Constant | | | | | `-1 Constant Value 1003.62 J/kg-K | | | | +-4 Thermal Conductivity Method Constant | | | | | `-1 Constant Value 0.0260305 W/m-K | | | | `-5 Turbulent Prandtl Number Method Constant | | | | `-1 Constant Value 0.9 | | | +-3 Gradients Gradient Method Hybrid Gauss-LSQ | | | | Limiter Method Venkatakrishnan | | | | Custom Accuracy Level Selector 2.0 | | | | Verbose false | | | | Least-Squares Quality Criterion true | | | | Flat Cells Curvature Criterion true | | | | Cell Skewness Criterion true | | | | Chevron-Cell Criterion true | | | | Least-Squares Tensor Minimum Eigenvalues Ratio 0.1 | | | | Normalized Flat Cells Curvature Factor 1.0 | | | | Maximum Safe (Positive) Skewness Angle (deg) 75.0 | | | | Minimum Unsafe (Positive) Skewness Angle (deg) 88.0 | | | | Use TVB Gradient Limiting false | | | | Acceptable Field Variation (Factor) 0.05 | | | +-4 Gravity | | | +-5 K-Epsilon Turbulence | | | +-6 Realizable K-Epsilon Two-Layer Buoyancy Production of Dissipation Boundary Layer Orientation | | | | Cmu 0.09 | | | | C1e 1.44 | | | | C2e 1.9 | | | | Ct 1.0 | | | | Sigma_k 1.0 | | | | Sigma_e 1.2 | | | | Sarkar 2.0 | | | | Tke Minimum 1.0E-10 | | | | Tdr Minimum 1.0E-10 | | | | Secondary Gradients On | | | | Convection 2nd-order | | | | Normal Stress Term false | | | | Curvature Correction Option Off | | | | Two-Layer Type Shear Driven (Wolfstein) | | | | Two-Layer ReY* 60.0 | | | | Two-Layer Delta ReY 10.0 | | | +-7 Reynolds-Averaged Navier-Stokes | | | +-8 Segregated Flow Minimum Absolute Pressure 1000.0 Pa | | | | Flow Boundary Diffusion true | | | | Unsteady Flux Dissipation Corrections false | | | | Limit Acoustic-CFL Option Per-Model | | | | Secondary Gradients On | | | | Convection 2nd-order | | | | Delta-V Dissipation Off | | | +-9 Segregated Fluid Temperature Secondary Gradients On | | | | Convection 2nd-order | | | | Flow Boundary Diffusion true | | | +-10 Steady | | | +-11 Three Dimensional | | | +-12 Turbulent | | | `-13 Two-Layer All y+ Wall Treatment Iterative Ustar false | | +-2 Reference Values | | | +-1 Gravity Value [0.0, -9.81, 0.0] m/s^2 | | | +-2 Reference Altitude Value [0.0, 0.0, 0.0] m | | | +-3 Minimum Allowable Temperature Value 0.0 C | | | +-4 Reference Pressure Value 1.0 atm | | | +-5 Minimum Allowable Wall Distance Value 1.0E-6 m | | | `-6 Maximum Allowable Temperature Value 4726.85 C | | `-3 Initial Conditions | | +-1 Pressure Method Constant | | | `-1 Constant Value 1.0 atm | | +-2 Static Temperature Method Constant | | | `-1 Constant Value 25.0 C | | +-3 Turbulence Specification Method K + Epsilon | | +-4 Turbulent Dissipation Rate Method Constant | | | `-1 Constant Value 0.1 m^2/s^3 | | +-5 Turbulent Kinetic Energy Method Constant | | | `-1 Constant Value 0.001 J/kg | | `-6 Velocity Method Constant | | | Coordinate System Laboratory | | `-1 Constant Value [0.0, 0.0, 0.0] m/s | `-4 Physics 2 Regions [mesh] | | Interfaces [Interface 1] | +-1 Models | | +-1 Circumferential Heat Flux Averaging | | +-2 Constant Density | | +-3 Gradients Gradient Method Hybrid Gauss-LSQ | | | Limiter Method Venkatakrishnan | | | Custom Accuracy Level Selector 2.0 | | | Verbose false | | | Least-Squares Quality Criterion true | | | Flat Cells Curvature Criterion true | | | Cell Skewness Criterion true | | | Chevron-Cell Criterion true | | | Least-Squares Tensor Minimum Eigenvalues Ratio 0.1 | | | Normalized Flat Cells Curvature Factor 1.0 | | | Maximum Safe (Positive) Skewness Angle (deg) 75.0 | | | Minimum Unsafe (Positive) Skewness Angle (deg) 88.0 | | | Use TVB Gradient Limiting false | | | Acceptable Field Variation (Factor) 0.05 | | +-4 Segregated Solid Energy Secondary Gradients On | | +-5 Solid | | | `-1 Al Database Material Al (Aluminum (pure)) [Standard/Solids] | | | `-1 Material Properties | | | +-1 Density Method Constant | | | | `-1 Constant Value 2702.0 kg/m^3 | | | +-2 Specific Heat Method Constant | | | | `-1 Constant Value 903.0 J/kg-K | | | `-3 Thermal Conductivity Method Constant | | | `-1 Constant Value 237.0 W/m-K | | +-6 Steady | | `-7 Three Dimensional | +-2 Reference Values | | +-1 Minimum Allowable Temperature Value 100.0 K | | `-2 Maximum Allowable Temperature Value 5000.0 K | `-3 Initial Conditions | `-1 Static Temperature Method Constant | `-1 Constant Value 25.0 C now, out of nothing(?) I see temperature raises quite rapidly but not pressure etc any ideas why? |
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September 12, 2014, 17:02
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#2 |
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New Member
Join Date: Sep 2014
Posts: 6
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anyone to help ?
thanks |
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September 15, 2014, 07:54
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#3 |
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Member
kris
Join Date: May 2014
Posts: 73
Rep Power: 11 |
Hi,
You could create a threshold to see where the temperature is rising and check if the mesh is good in those locations. If the mesh is not so good, you could try and change the mesh. |
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September 15, 2014, 16:47
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#4 | |||
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Quote:
Quote:
Also, what I dont know how important but there is a message: Quote:
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September 16, 2014, 05:25
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#5 |
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Member
kris
Join Date: May 2014
Posts: 73
Rep Power: 11 |
I cannot find anything wrong with your mesh statistics.
Make sure your interfaces are good. What I was suggesting is that you create a threshold for temperature above your expected maximum. For eg. if you are expecting the max temperature would be about 400 C, create a threshold for temperature > 500 C. As you run your simulation, look at the threshold. This will show you where the temperature is initially going high. This would give you a better idea of what is happening. |
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September 16, 2014, 05:46
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#6 |
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New Member
Join Date: Sep 2014
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well, I cannot say much about interfaces , as they are not used much
also, boundary conditional etc does not contain any temperature differences.. Literally no ideas where such, immediate temp. raise is coming from also, temperature raises pretty much on the velocity vector of the flow any help in "debugging" is welcome ! |
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