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What you asked us in August

By Chloe Allison 17 September 2020

Welcome back to our monthly review of your support questions! Let’s take a look at the common OnScale support questions from August.

Why is my circuit not affecting my impedance?

When you connect a circuit to an electrode, for example a capacitor, then you calculate the impedance of the device in Post Processor, there will be no change between the impedance without a circuit and the impedance with a circuit. This is because the Post Processor calculation uses the charge at the device which will remain unchanged. You need to extract the charge at the source to see the effect of the circuit.

Circuit voltage and charge data are stored in the crtv(i) and crtq(i) data arrays. These arrays are one-dimensional arrays whose indices represent a specific degree-of-freedom (dof) for the group of circuits connected to the model electrodes. The code prints a table identifying which degree-of-freedom is at which point in the circuit. An example of this data in a *.flxprt file is:

Electrode  1  name=top   number of nodes=  101

Electrode  2  name=botm  number of nodes=  101

 

Indices of circuit unknowns in crtq and crtv arrays

————————————————–

Electrode top           1

sers rest  1.0000E+00   2  3

shnt cpac  6.0000E-08   4  5

sers indc  3.0000E-08   6  7

Source                  8

 

This code shows that there are 8 dof for the circuit solution matrix for this problem. They correlate with the locations shown in the circuit diagram below. Note that, except for the electrode and the source, there are two dof representing the circuit state on both sides of each circuit component. Often, there is more than one dof at the same physical location in the circuit. For example, dof 1 and 2 are at the same location and likewise for dof 3, 4 and 6. At junctions like these, the voltages are equal and the charges sum to zero. This means that for a junction of two dof, the two charge values will have the same magnitude but different signs.

Transducer

Specific charge data can be output using pout hist. For example:

pout hist crtq 1 8 1

outputs the charge at the source.

Does geom bend affect my material properties?

When using the geom bend command, a rectangular mesh can be bent into an arc. If a transversely isotropic material is specified using the stiffness tensor input and assigned Cij entries that correspond to different directions in Hooke’s law, these stiffness entries are not mapped according to the global coordinate system after bending (output xcrs, ycrs) but the initial coordinate system (output xcrd, ycrd).

geom bend only applies to the geometrical structure, not the material properties. To rotate the material properties, apply a local cylindrical axis definition to the material using matr axis.

Why has my model failed with ‘insufficient core hours’ when I have enough core hours?

Before running a job, you should check that the estimated Core-hour burn does not surpassthe maximum CHs allowed by your account. To checkthis go to the Portal > Accounts > Account Access and see the Maximum Core Hours Per Request:

OnScale

This sets the maximum number of Core-hours that can be used in one job. If this is not large enough for a job it may fail so be careful of this. To edit, click on the email address and then Save.

What to do when my job fails because of ‘insufficient memory allocation’?

We have written a blog all about cloud estimation and memory assignment that should help you tackle this error. Check it out here.

That is all for this month. If you have any questions that have come out of reading this blog post, feel free to ask them on our forum!

Chloe Allison
Chloe Allison

Chloe Allison is an Application Engineer at OnScale. She received her MA in Electrical and Electronics Engineering from the University of Strathclyde. As part of our engineering team Chloe assists with developing applications, improving our existing software and providing technical support to our customers.