Master Thesis - 3D CFD Modeling of Thermosiphon Heatsinks

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About this opportunity:

Thermosiphon heatsinks are passive cooling solutions for high-power electronics that use phase-change heat transfer and natural circulation without mechanical pumping. Predicting their performance requires understanding complex two-phase phenomena such as evaporation, condensation, liquid return, and vapor transport.

This thesis will focus on developing and applying three-dimensional Computational Fluid Dynamics (CFD) models using the Volume of Fluid (VOF) method. You will investigate how operating conditions and design parameters affect thermosiphon performance and evaluate the accuracy and applicability of detailed numerical models. Depending on project progress, simplified segment-based models may also be explored and compared with the VOF results.

The project is for one student (30 hp) and will be based at Ericsson AB in Kista, Stockholm. Preferred starting date: January 2027.

What you will do:

• Review thermosiphons, two-phase cooling, and relevant CFD modeling approaches.
• Develop and run 3D VOF simulations of thermosiphon heatsinks.
• Analyze evaporation, condensation, liquid return, vapor transport, and overall flow behavior.
• Study the effects of operating conditions, geometry, and filling ratio on thermal performance.
• Evaluate thermal resistance, temperature distribution, and key flow characteristics.
• Document modeling challenges and best practices, and provide recommendations for future thermosiphon design.
• Optionally compare simplified segment-based models with detailed VOF simulations.

The skills you bring:

• You are pursuing a Master's degree in Mechanical Engineering, Engineering Physics, Energy Technology, Applied Physics, or a related field.
• Previous experience with Computational Fluid Dynamics is required.
• Good understanding of fluid mechanics, thermodynamics, and heat transfer.
• Strong analytical and systematic problem-solving skills.
• Ability to work independently and communicate technical findings clearly.
• Experience with multiphase flow, phase-change phenomena, programming, or numerical methods is an advantage.

Why join Ericsson?At Ericsson, you´ll have an outstanding opportunity. The chance to use your skills and imagination to push the boundaries of what´s possible. To build solutions never seen before to some of the world's toughest problems. You´ll be challenged, but you won't be alone. You´ll be joining a team of diverse innovators, all driven to go beyond the status quo to craft what comes next.

Primary country and city: Sweden (SE) || Stockholm

Req ID: 787558