CTSP (Contamination Transport Simulation Program)
CTSP (Contamination Transport Simulation Program) is a program for simulating molecular and particulate contamination transport. The need to model contamination is commonly encountered in vacuum and aerospace industries. Plastics and other organic materials exposed to low pressures outgas unspent hydrocarbons which then deposit onto sensitive surfaces such as camera lenses or radiators. Other components may be sensitive to particulates. These are tiny dust particles arising from air pollution, garments, or flaking off paints. Particulates are present on all surfaces but can redistribute during vibrational events such as spacecraft launch or on-orbit deployments.
CTSP models the transport of molecular and particulate contaminants from their sources to the eventual settling locations in order to estimate the end of life cleanliness levels. The code utilizes a kinetic method in which the contaminants are represented by particles, which are advanced through small time steps. This allows the code to take into account aerodynamic, gravitational, or electrostatic forces. Unlike Monte Carlo ray tracing tools, CTSP concurrently simulates the entire contaminant population. This allows the end user to visualize the contaminant plume partial pressures and bulk streaming velocities. It also allows the code to simulate the transition rarefied gas regime such as chamber repress in which inter-molecular collisions become important. CTSP supports highly detailed, multi-million element surface meshes to represent the geometry. It also implements multiple contamination-specific material sources, including a detailed model for molecular outgassing and particulate generation. Molecular surface adhesion and desorption physics is governed by surface temperature and material activation energy.
- Support for highly complex geometries loaded from surface mesh files in common formats such as OBJ, STL, Nastran, UNV, and TSS
- Detailed model for molecular outgassing, which takes into account surface desorption and adsorption from the gas phase
- Particulate generation per IEST-STD-1246D and ISO-14644-1 industry standards
- Material activation energy and time-dependent surface temperature used to compute sticking probability
- Drifting Maxwellian and effusion sources to model venting of internal cavities
- Multiple simulation particles traced concurrently, allowing visualization of contaminant plume densities
- Support for external gravitational, aerodynamic, and electrostatic forces
- Intermolecular collisions can be included via DSMC
- Simulation results saved in VTK or Tecplot format. Support for saving surface, volume, and particle data.
- Support for multithreading and parallel processing with MPI
Single-user licenses are available to US customers. Please contact us for pricing information.
A handout is available here: CTSP-flyer.pdf
Below are examples demonstrating the code’s ability to resolve complex geometries, and model transport of molecular and particulate contaminants. Input files for these examples are included in the distribution package.
This browser-based GUI can be used to generate and edit CTSP input files (you can also open it in a full window). The GUI runs locally on your machine – no data is sent to our server. Start by either loading an existing ctsp.in file, or use the Add Operation to create a new op. The “down arrow” should show the list of available options, or you can refer to the op index. Some users have reported incompatibility with Internet Explorer. If that’s the case, please try Firefox or Chrome.
CTSP User’s Guide: CTSP-UG.pdf
- 1.0: Complete code base rewrite to follow modern C++ paradigms, automatic time step sub-cycling, tapelift source, surface histograms, reduced memory footprint for flow data.
- L. Brieda, “Numerical Model for Molecular and Particulate Contamination Transport”, AIAA J. Spacecraft & Rockets, published online, October 2018 (link)
- L. Brieda, “Molecular Contamination Modeling with CTSP”, Proceedings of 30th International Symposium on Rarefied Gas Dynamics, Vol. 1786, No. 01, 2016, http://doi.org/10.1063/1.4967536 (pdf)
- L. Brieda, “Molecular Outgassing and Deposition in EP Applications”, 34th International Electric Propulsion Conference (IEPC), Kobe, Japan, 2015 (pdf)