wireless power transfer by pcb coil

March 10, 2013, 8:48 am

≫ Next: Using both pressure point and outlet with Pressure, no viscous stress?

Dear All,

I want to model and simulate a wireless power transfer module. Its application is in microchip implant.

The model has two 3D microstrip(PCB with substrate) coil. One for transmitter and the other is for receiver. My model has two physics:

1) Magnetic and electric Fields

2) Electrical Circuit

Electrical circuit supplies Sin power to transmitter in 4MHz frequency. The receiver coil is connected to a resistor load. I use terminal in magnetic and electric field to connect the 3D model to circuit.

I want to study electrical field (E) and magnetic field (H) in 3D model. Also, I want to study how much power transfer and how much is the efficiency.

I use frequency domain study and stationary or Time Dependent study, but in frequency domain I got error in convergence and in time dependent the circuit can’t stimulate the 3D model.

How can I solve this problem?

Is there any idea to get my goal results?

I attach this model in this share link you can download it here:
www.4shared.com/file/BHB8du0n/power.html

So Thanks.

Mina

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Using both pressure point and outlet with Pressure, no viscous stress?

March 11, 2013, 5:50 am

≫ Next: Heating Circuit

≪ Previous: wireless power transfer by pcb coil

Hi!

I'm working with natural and forced convection with the aim to design a ventilation/heating system for my master's thesis.

I'm wondering if I need a "Pressure Point Constraint" if I'm using an outlet with "Pressure, no viscous stress" or if they will cause trouble for each other?

Thanks!

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Heating Circuit

March 11, 2013, 7:19 pm

≫ Next: Equation Based Modeling in structure mechanics

≪ Previous: Using both pressure point and outlet with Pressure, no viscous stress?

Hello,

I am modeling a model very similar to heating circuit in the model library of Comsol 4.3a (physics are electric current shell, shell and thermal stress). The only differences are dimensions and materials. The dimensions are smaller and the materials are Si and Al instead. The strange things that happens is that Comsol does only one iteration and stops solving in the second equation at the segregated group 1 which is the thermal stress variables. Unfortunately the error is: The relative error is greater than the relative tolerance. The temperature group seems to be right even with one iteration but the strains don't look right.

I set up everything the same as the model from the model library but it does not work.

I tried different mesh sizes and types. I also tried different solvers.

What do you think is my error source?

Thank you so much for your help.
Best,
Hamideh

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Equation Based Modeling in structure mechanics

March 12, 2013, 7:17 am

≫ Next: Error: 7161 The mass matrix is zero - resolve

≪ Previous: Heating Circuit

Hi All,
While solving equation based structure mechanics problem i encountered the following error message-

- Undefined value found.
- Detail: Undefined value found in the stiffness matrix.
-There are 2020 equations giving NaN/Inf in the matrix rows for the variable mod1.u at coordinates: (4.68675e-037,0.000125,-7.65404e-021), (7.65404e-021,0,-0.000125), (5.41223e-021,8.83883e-005,-8.83883e-005), (-1.40602e-036,-0.000125,2.29621e-020), (5.41223e-021,-8.83883e-005,-8.83883e-005), ...

-There are 1519 equations giving NaN/Inf in the matrix rows for the variable mod1.v at coordinates: (4.68675e-037,0.000125,-7.65404e-021), (7.65404e-021,0,-0.000125), (5.41223e-021,8.83883e-005,-8.83883e-005), (-1.40602e-036,-0.000125,2.29621e-020), (5.41223e-021,-8.83883e-005,-8.83883e-005), ...

-There are 2020 equations giving NaN/Inf in the matrix rows for the variable mod1.w at coordinates: (4.68675e-037,0.000125,-7.65404e-021), (7.65404e-021,0,-0.000125), (5.41223e-021,8.83883e-005,-8.83883e-005), (-1.40602e-036,-0.000125,2.29621e-020), (5.41223e-021,-8.83883e-005,-8.83883e-005), ...
and similarly for the degrees of freedom, NaN/Inf in the matrix columns.

Can anyone please suggest why this type of error is coming and how to remove it?

Thank You

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Error: 7161 The mass matrix is zero - resolve

March 12, 2013, 11:59 am

≫ Next: Prolonged error with "Last Time Step Not Converged"

≪ Previous: Equation Based Modeling in structure mechanics

Respected sir/ma'am,

I am trying to simulate a Nano ElectroMechanical Switch(NEMS) using the following modules:a)solid, stress-strain, b) Moving Mesh, and c)Electrostatics.
When i run the solver, it shows an error message:'Error: 7161 The mass matrix is zero' along with a warning: 'Not all domains are meshed'.
The sizes are in nano domain. Model is attached for your kind reference.
For meshing i used Mapped Meshing to reduce number of elements.
I am using Version 3.5a on Pentium processor with 32 bit and 2 GB RAM.

Thank You in advance

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Prolonged error with "Last Time Step Not Converged"

March 13, 2013, 1:40 am

≫ Next: How can I find the flow velocity of a specific coordinate point

≪ Previous: Error: 7161 The mass matrix is zero - resolve

Dear sir,

We were trying out "PIPE FLOW MODULE" as you have suggested. And thanks for the advice, as it has reduced the number of mesh elements to a larger extent. But, we were getting a consistent error message namely,

"Error:

Failed to find consistent initial values.
Segregated group 2

COMSOL assertion failure.
Last time step is not converged.

Warning:

SOR line did not find any lines. "

I would like you to verify our model and help us if any errors made in the modeling.

Basic parameters are that, the heat flux will take place in walls through inner air, atmospheric air and water in pipes as in the model. I would be so grateful, if our prolonged error is sorted out.

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How can I find the flow velocity of a specific coordinate point

March 13, 2013, 12:44 pm

≫ Next: Automatically parameter increasing

≪ Previous: Prolonged error with "Last Time Step Not Converged"

Dear all,

I would like to ask how can I find the flow velocity of a specific point (x=105, y=2.5) in my channel (it is shown in the picture). In the graph, if I click at any random point I got 3 values: on the x axis I got the channel's length, on the y axis the height and the different colours represent the flow velocity profile and hence, I got 3 values for x,y and u.

But I would like to find my velocity at a specific point, so could you pleqse help me how can I do that?

Thank you a lot beforehand.

Regards

Dimitrios

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Automatically parameter increasing

March 13, 2013, 1:26 pm

≫ Next: "Reinitializing GUI" for a long time

≪ Previous: How can I find the flow velocity of a specific coordinate point

Dear friends,
I have a simple 2D rectangular model, I want to measure some acoustic properties in my desired frequency range, for specific height of model it's easy, but I want to check a range of heights for example 0.1 mm to 10 mm, with 0.1 increment, how can I set COMSOL to do this and save data automatically?
Regards

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"Reinitializing GUI" for a long time

March 14, 2013, 6:35 pm

≫ Next: Solve PDE on 1D domain?

≪ Previous: Automatically parameter increasing

Hi, when I solve a PDE, it takes a lot of time. I closed the programme with task manager of windows. When I reopen the file, the programme is "reinitializing GUI" . I wait for almost an hour and nothing changed. At this time I cann't do anything else in the software. How can I solve this problem?

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Solve PDE on 1D domain?

March 15, 2013, 9:33 am

≫ Next: Time dependent simulation

≪ Previous: "Reinitializing GUI" for a long time

Hy guys, I have a problem with solving a PDE based model defined by me, it is not a default template in COMSOL.

My problem is that the equation is solved for the time domain, but not for the geometry specified. ( Interval )

Does the solver automatically solve with respect to 'x axis' ( it represents the height of a reactor x=[0,20] m )?

The PDE I'm trying to solve is the following:
dT/dt=-VL*dT/dx-constant

where VL and constant are known.

Could you help me with this,

Thank you.

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Time dependent simulation

March 15, 2013, 11:43 am

≫ Next: How to combine the Frequency Domain and Coil Current Calculation

≪ Previous: Solve PDE on 1D domain?

Hello Ivar,

I need a big favor from you.
Its a request since my model is giving weird results. I have worked on it but I need to get the physics right.

So I decided to try the time dependent study which should give the instantaneous current values which are then used in the stationary study, that is my thinking.

So I created current variables in the parameters section, ix and iy. These currents are dependent on time, t. So I thought the parameters will be able to access the variable t, but ????

I defined the current in a coil as -ix on one coil-side and +ix on the other coil-side, is this right in the multi-turn coil domain under MF.

The other difficulty I faced is defining relative permeability which will change depending on the H and B values for non-linear material, since mu_r = 1/mu_0 * B/H, where B and H are from the BH curve.
So how do you go about this issue. I was not able to define relative permeability as defined above.
I also Imported with both the 1st and 3rd quadrant, you can check a plot to see how it looks like and I hope its OK.

From the plots of the magnetic vector component, it can be seen that the flux is not penetrating the silicon steel sections ????

Regards and thanks in advance
NB: I attached an m-file by mistake but the model is as attached.
I also submitted the same to the technical support.

Wanjiku

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How to combine the Frequency Domain and Coil Current Calculation

March 15, 2013, 12:33 pm

≫ Next: COMSOL in parallel mode: a speedup of 20% using 4 cores?

≪ Previous: Time dependent simulation

Hello everyone,

i´m trying to simulate an numerical coil with alternating current. The coil is built with the "Multi-Turn Coil Domain". My coil type is numeric wich requires an additional "Coil Current Calculation" step before my "Frequency Domain" step in my study. I solved it for 50,500,5000 Hz and looked at the coil paramters. My coil excitation is set to 0.15A wich should be the coil current for all frequencies. The "Coil voltage" and "Coil resistance" should be different for each frequency which is not, if i do a global evaluation for those two parameters.
Anyone got an idea how i can solve my problem? I´m attaching my modelfile, if someone is willing to take a look at it.

Best wishes,
Andreas Schneider

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COMSOL in parallel mode: a speedup of 20% using 4 cores?

September 23, 2009, 1:01 am

≫ Next: Java Runtime Environment error

≪ Previous: How to combine the Frequency Domain and Coil Current Calculation

Hello everyone,

I have performed the following experiment. Using the command -np #cores, I have forced COMSOL Multiphysics to use 1, 2, 4 or 8 of the available cores on my computer. I also used the default configuration of COMSOL Multiphysics, i.e, without the command -np. I performed the experiment using two models comprising two drift-diffusion equations coupled with the Poisson equation - one is quasi-linear, the other is highly non-linear. The solver used was Pardiso. The results are in the attached file.

I have obtained a speed-up of about 20% when I activated 4 cores, as compared with the duration of calculations using only 1 core. Do you believe that this improvement of 20% is the typical speedup that can be obtained? Does anyone have some more data or experience on this issue?

Thank you for your help.

Kind regards,
Pedro

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Java Runtime Environment error

July 28, 2011, 2:37 am

≫ Next: negative concentrations with high reaction terms in biokinetic models

≪ Previous: COMSOL in parallel mode: a speedup of 20% using 4 cores?

Getting following error,

A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x0000003da3efbc6c, pid=6909, tid=46912497239488
#
# JRE version: 6.0_20-b02
# Java VM: Java HotSpot(TM) 64-Bit Server VM (16.3-b01 mixed mode linux-amd64 )
# Problematic frame:
# C [libgtk-x11-2.0.so.0+0xfbc6c] gtk_icon_set_render_icon+0x58c

Does anyone know how to resolve it...

Regards

↧

negative concentrations with high reaction terms in biokinetic models

September 26, 2011, 4:46 am

≫ Next: Piezoresistive modeling

≪ Previous: Java Runtime Environment error

Hi,

I am using a biokinetic model based on the ASM (activated sludge models) to simulate water contaminant removal in a gravel filter. This kind of models consider the degradation of the influent solute components by several species of microorganisms. As a result of the degradation, this microorganisms also grow.

For the flow simulation I am using Darcy's Law. The contaminant removal is modeled using the solute transport module with a reaction term, in which monod-like expressions are deffined. These reaction expressions are also multiplied by the concentration of the different species of microorganisms that consume each solute component (the higher the concentration of microorganisms the more they consume).
The growth of bacteria is modeled using PDE general form expressions.

This works just fine for short periods of time (e.g. 1 day), but when bacteria start to grow considerably, the reaction terms become very big and negative (consumption), and thus the concentrations of the solutes become also negative. I've tackled this by deffinig variables s=max(eps^2,S), were S is the concentration of the solute. So when S becomes negative, in the next time step it is seen as a 0 instead of a negative value. If I don't do this, a part from getting negative solute concentrations, the growth of bacteria also gets corrupted (as it depends on S), and therefore this error impacts the whole model. I also tried to add expressions such as *(S>0) in the reaction term of S, but I have not been successful either.

I have checked the solutions suggested in this link, www.comsol.com/support/knowledgebase/952/ but it did not help much.

Could anyone tell me how to make the reaction rate 0 when the concentration of the substrate becomes zero? I do not understand where exactly should I introduce the term max(eps^2,Q).

Hope I made myself clear.

Thank you in advance

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Piezoresistive modeling

May 29, 2012, 8:26 am

≫ Next: COMSOL Failing at Simple DE?

≪ Previous: negative concentrations with high reaction terms in biokinetic models

Hello all

I want to simulate a piezoresistive beam with Comsol.
I was looking to find an example of piezoresistive modeling to find out what module they usually use and how are the settings but i didn't find any
It seems there was an example of "piezoresistive elevator button" before for old version of Comsol. But it is not avail;able anymore.
Can anyone send me this example or any other helpful link about piezoresistive simulation by Comsol?

Best
Bahar

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COMSOL Failing at Simple DE?

February 28, 2013, 3:16 pm

≫ Next: Heating Circuit

≪ Previous: Piezoresistive modeling

I've encountered a very simple problem with COMSOL's eigenvalue solver and I was wondering if anyone else has had the same problem.

I'm trying to solve the simplest DE imaginable. I'm trying to find eigenmodes for the 1D wave equation.

Governing Equation:
phixx = - lambda*phi

Domain:
x in [0, pi]

Boundary Conditions:
phi(0) = phi(pi) = 0

I'm using the eigenvalue solver in the General Form PDE module.

The solutions to this problem are sine waves. phi = A*sin(sqrt(lambda)*x), where lambda = n^2 for an integer n. COMSOL solves this problem fine.

The problem comes if I try to solve this problem by introducing an auxiliary field, beta.

Governing Equation:
phix = beta
betax = -lambda * phi

Domain:
x in [0,pi]

Boundary Conditions:
phi(0) = phi(pi) = 0

This should be an equivalent problem, but COMSOL is not able to solve it correctly. All of the modes it gives me look like garbage. Frankly, I'm beginning to distrust my previous results in COMSOL because of this issue...

Has anyone encountered anything like this before?

Any help would be appreciated,
-Julian

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Heating Circuit

March 11, 2013, 2:19 pm