When Are Core Hours Deducted from your Account?

In SimScale, core hours serve as the currency for computational resources used during simulations and meshing operations. One core hour equates to running a simulation for one hour on a single processor core. For example, utilizing 2 processor cores for one hour will consume 2 core hours.

This article outlines the various scenarios in which core hours may be deducted from your account, depending on how a simulation run concludes.

When Core Hours Are Deducted?

Core hours are deducted from a user’s account based on the simulation running as expected. If the simulation does not complete, the deduction occurs only when the user chooses to cancel the operation or when it’s canceled automatically after reaching the maximum runtime.

An easy way to check if a particular operation consumed core hours is by observing its color: green and yellow indicate that core hours were consumed.

There are three possible scenarios:

1. Successful simulations and meshing operations: When a simulation or meshing operation completes successfully, the corresponding core hours are deducted from your account. To view the exact amount of resources consumed, click on the completed operation.
2. Canceled simulations: Manually canceling a simulation or meshing operation in SimScale will result in the consumption of core hours up to the point of cancellation. As a sidenote, the last successfully calculated step is typically saved and should be available for post-processing. This allows you to analyze the partial results obtained before the cancelation.
3. Simulations exceeding maximum runtime: Under Simulation Control, users can define a Maximum Runtime for their simulations. If a simulation exceeds this specified duration, it will be automatically canceled. It’s important to note that even in such cases, core hours corresponding to the computational resources used up to the point of cancellation will be deducted from your account.

When Core Hours Are Not Deducted?

If a simulation fails unexpectedly due to a system issue, core hours are not deducted from your account. In such cases, the operation will be highlighted in red, indicating a system failure.

There are two main ways this can occur:

1. Failed simulations due to system errors: If a system error occurs (e.g., divergence in a CFD simulation, matrix not factorizable in an FEA case, issues during material model integration), as shown in Figure 2, this will not result in core hour usage.
2. Automatic restarts/cancelations due to resource limitations: When the machine allocated to run the operation encounters issues, such as becoming ill or running out of memory (causing the process to fail or restart), no core hours are used from your account.