I am trying to extract the inductance of a two conductor bus bar using full wave simulation. The source is excited with a discrete port and a short is created on the far end with a lumped port. 

The two bus bars are of the following dimensions: 1000mm*60mm*10mm 

Spacing between the bus bars is 2mm

The inductance above 100 kHz seems quite accurate and matches the closed form expression. 

The inductance from 1 Hz to 100 Hz seems incorrect. I expect the low frequency (close to DC) inductance to be flat until skin depth and then drop to a lower value. Can you let me know where my settings are going wrong? 

I also checked a rectangular loop of wire (170mm*23.5mm with radius of 0.5mm) and have the same issue so it appears to be a setting issue. 

Any insight will be much appreciated. 

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