Initial Boundary Conditions and ElecNode Configuration


I’m currently working on a spacecraft simulation and could use some guidance regarding setting up the initial boundary conditions (potential). I’ve encountered a discrepancy between the specified potential conditions and the simulation results, especially in the early time steps when reviewing the time series data.

Here are my primary concerns:

  1. Face Group Potential (SCDiriPotSurf[V]): I’ve adjusted the default potential for the face group to reflect the desired initial condition on the spacecraft’s surface. However, it appears that the potential doesn’t align with the expected initial state during the early simulation steps. Should I also consider modifying the node potential (SCDiriPos[V]) to address this issue?
  2. ElecNode Configuration: In my simulation, I’m working with two spacecraft, each with its own set of face groups. Additionally, there are face groups for the external boundary and the computational volume. To accurately simulate the interactions between these entities, I’d like to clarify the recommended ElecNode configuration. How should ElecNodes be defined for the two spacecraft, external boundary, and computational volume?

Your insights and expertise on this matter would be greatly appreciated. If you have experience with spacecraft simulations or similar scenarios, I would be grateful for any guidance or best practices you can offer.

Thank you for your assistance!

Hi Mary!

A late reply might be better than none.

(1.) Indeed, I was told to modify both the face and node potential (SCDiriPot) when using initial Dirichlet potentials and have had success doing so.

(2. ) I haven’t simulated two spacecraft before, but in any case there should be no electrical nodes defined for the external boundary or computational volume when simulating spacecraft, and indeed the way to do that while using the default group parameters for boundary and volume groups is not obvious… The other spacecraft nodes should be defined as usual, with at least one of them defined as node 0, and you can set the circuitry between two nodes of your choosing as you wish.

Maybe I’m reading into this a bit, but it it almost sounds like you are looking for fixing the potential of one surface w.r.t to infinity. You can manipulate the potential for all surfaces, via the dirichlet conditions and then setting electricCircuitIntegrate = 0, to just study how the plasma reacts to such potentials. If you want to fix one surface and not the others ( a rather unphysical case, but maybe interesting) I think you can hack it by running a slow Langmuir Probe simulation on one of the nodes, setting “stepped potential” w.r.t. to a plasma at infinity, but there’s no guarantees, and potentially a lot of work.

Best of luck