I have searched for the mid-point and smoothening in documentation still not been able to get their significance into the same.
Please see the attached model :
Now it is showing error as:
Segregated group X1
System matrix is zero.
Sorry to bother you , please let me know from where I can read well about this step function. It would be better if you please share your contact detail .
Ishant
Thanks again ,
Could you please share you contact detail or add me on skype : ishantj or gtalk : ishantmiet@gmail.com
Ishant
In the model you attached there is no trace of what you wrote.
However, I think I can gather what you did. Let us go over the instructions again:
1) right click on the Definitions node and select Functions and the Step. This will create a function called step1(t), now define the proper mid-point and smoothing.
2) in the Inlet node multiply the velocity by the step1(t) function you defined beforehand.
3) in the Step 1: Time Dependent node uncheck the box near the Non-Isothermal Flow 2 physics so that the solver wll work on the Non-Isothermal Flow physics only.
For the rest you ought to begin with a smaller velocity, but it is up to you whether to do it.
I have made the necessary changes in the model attached below. Please check it .
I am here explaining you the whole problem:
A producer gs is flowing with a flow rate of 11.76m/s through a small inlet of 20cm diameter( shown as 10cm due to asymmetric model) of a cylinder shape vessel with two outlet for the model of 10 cm diameter,
The cylinder is lined with refractory lining 0f 30cm thickness ans covered with 10cm steel cage.
For unsteady case : I have implemented what you suggested in your earlier mail but it is showing error as :
Error 1: Syntax error in expression.
- Expression: 11.76 * Step 1 (t)
- Subexpression: 1 (t)
- Position: 14
Error 2: Failed to find a solution.
Maximum number of segregated iterations reached.
Returned solution has not converged.
Since i have increased the no of time steps but it is still showing the same error.
Please look inti it and reply asap.
Ishant
1) in the Inlet node you are prompted to choose a type of boundary condition, if you choose velocity then you must write down the value/expression of the velocity. That very value/expression must be multiplied by a time function which grows smoothly from zero to your desired final value, an example
Velocity:
11,1*step1(t)
You need to define the step1 function in the Definitions node of your model. You didn't do in the last model you uploaded.
In the Time Step node you are solving both the physics of your model, you need to check only the physics you are interested in. It seems the error is due to the fact that both Non-Isothermal Flow and Non-Isothermal Flow 2 boxes are checked, I would deselect the second one.
2) there is no way you can solve Re=220.000 with a laminar mode, what type of errors did you get with the turbulent one? I have been havign several issues too with the turbulent model I am quite interested in having some more infos.
I think it would better first look at these two issues before thinking about the high temperature and the long span of time you want to simulate.
Thanks for your prompt response.
Please note that :
1.Your first point is not clear regarding which step or what should be multiplied
2.First i was working on turbulent flow but not getting the right result so tried on laminar flow.
3.Inlet temp i.e Fluid temperature that is flowing inside with certain velocity have the temperature of 2200 deg C, It will heat up the refractory lining ( Brick of magnesite) upto a temp rage of 1600-1700 , so the usual temp range for the steel shell would be around 300- 500 degC
Please help me in this regard.
IShant
Some observations:
1) Your inlet velocity needs to be multiplied to a smoothly increasing function like 'step' so that the software can begin to solve from a 0 value and then reach a solution.
2) Your inlet velocity is 11 m/s and the inlet is 10 cm, coupled with the dynamic viscosity of your fluid, the corresponding Reynolds number is 220.000, i.e. fully turbulent flow, are you sure the velocity is that high?
3) Your inlet temperature is above 2200°C, steel is going to melt at that temperature, are you sure it needs to be that high?
PFA is the model .
Please see the attached model :
Now it is showing error as:
Segregated group X1
System matrix is zero.
Sorry to bother you , please let me know from where I can read well about this step function. It would be better if you please share your contact detail .
Ishant
Thanks again ,
Could you please share you contact detail or add me on skype : ishantj or gtalk : ishantmiet@gmail.com
Ishant
In the model you attached there is no trace of what you wrote.
However, I think I can gather what you did. Let us go over the instructions again:
1) right click on the Definitions node and select Functions and the Step. This will create a function called step1(t), now define the proper mid-point and smoothing.
2) in the Inlet node multiply the velocity by the step1(t) function you defined beforehand.
3) in the Step 1: Time Dependent node uncheck the box near the Non-Isothermal Flow 2 physics so that the solver wll work on the Non-Isothermal Flow physics only.
For the rest you ought to begin with a smaller velocity, but it is up to you whether to do it.
I have made the necessary changes in the model attached below. Please check it .
I am here explaining you the whole problem:
A producer gs is flowing with a flow rate of 11.76m/s through a small inlet of 20cm diameter( shown as 10cm due to asymmetric model) of a cylinder shape vessel with two outlet for the model of 10 cm diameter,
The cylinder is lined with refractory lining 0f 30cm thickness ans covered with 10cm steel cage.
For unsteady case : I have implemented what you suggested in your earlier mail but it is showing error as :
Error 1: Syntax error in expression.
- Expression: 11.76 * Step 1 (t)
- Subexpression: 1 (t)
- Position: 14
Error 2: Failed to find a solution.
Maximum number of segregated iterations reached.
Returned solution has not converged.
Since i have increased the no of time steps but it is still showing the same error.
Please look inti it and reply asap.
Ishant
1) in the Inlet node you are prompted to choose a type of boundary condition, if you choose velocity then you must write down the value/expression of the velocity. That very value/expression must be multiplied by a time function which grows smoothly from zero to your desired final value, an example
Velocity:
11,1*step1(t)
You need to define the step1 function in the Definitions node of your model. You didn't do in the last model you uploaded.
In the Time Step node you are solving both the physics of your model, you need to check only the physics you are interested in. It seems the error is due to the fact that both Non-Isothermal Flow and Non-Isothermal Flow 2 boxes are checked, I would deselect the second one.
2) there is no way you can solve Re=220.000 with a laminar mode, what type of errors did you get with the turbulent one? I have been havign several issues too with the turbulent model I am quite interested in having some more infos.
I think it would better first look at these two issues before thinking about the high temperature and the long span of time you want to simulate.
Thanks for your prompt response.
Please note that :
1.Your first point is not clear regarding which step or what should be multiplied
2.First i was working on turbulent flow but not getting the right result so tried on laminar flow.
3.Inlet temp i.e Fluid temperature that is flowing inside with certain velocity have the temperature of 2200 deg C, It will heat up the refractory lining ( Brick of magnesite) upto a temp rage of 1600-1700 , so the usual temp range for the steel shell would be around 300- 500 degC
Please help me in this regard.
IShant
Some observations:
1) Your inlet velocity needs to be multiplied to a smoothly increasing function like 'step' so that the software can begin to solve from a 0 value and then reach a solution.
2) Your inlet velocity is 11 m/s and the inlet is 10 cm, coupled with the dynamic viscosity of your fluid, the corresponding Reynolds number is 220.000, i.e. fully turbulent flow, are you sure the velocity is that high?
3) Your inlet temperature is above 2200°C, steel is going to melt at that temperature, are you sure it needs to be that high?
PFA is the model .