Microwave heating

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Microwave heating

Microwave heating of liquids is a very complex, non-linear three-way coupled problem, where electromagnetics, fluid dynamics and thermal energy are coupled through convective heat transfer and temperature dependent properties such as permittivity, density, viscosity, and phase change. To make things even more challenging, fluids can be represented either with Newtonian (water, alcohol) or Non-Newtonian (ketchup, resin) viscosity models. We have numerical models for different kinds of fluids and all common microwave excitation ports, including magnetron antennas and rectangular waveguides.

Continuous flow microwave heating is a new technology for volumetric heating of liquid food products.

MW heating apparatus

Continuous microwave heating

Heat transfer in fluids and gases takes place in conductive and convective ways. Turbulent flow has an additional convective term that increases the efficiency of the overall heat transfer process therefore applying a volumetric heat source on turbulent flow helps efficiently spread it and reduces the risk of hot spots.


Electromagnetic models that are used in simulations include two microwave heating mechanisms


– Dielectric (polarization)
– Conductive


Both these loss models oftentimes are included in the imaginary part of permittivity which represents energy absorption by material. For a fixed frequency (e.g. 2.45 GHz) temperature-dependent permittivity given as complex functions ɛRe(T) and ɛIm(T) represent real and imaginary parts.

Temperature distribution

Velocity distribution

Research has shown that our models are oftentimes faster and more robust than commercial FEM packages.

Our software solution consists of well-known open-source simulation packages Elmer FEM (microwaves) and OpenFOAM (fluid dynamics) that are coupled using our software EOF-Library. EOF-Library enables efficient internal field interpolation and communication of heat loss and temperature data between two simulation packages.

SIA EOF Consulting ir noslēdzis 28.02.2020 līgumu Nr. VP-L-2020/12 ar Latvijas Investīciju un Attīstības Aģentūru par atbalsta saņemšanu vaučera programmas ietvaros. Pētījuma mērķis ir veikt eksperimentālo izstrādi, lai atrisinātu 3 industriālu problēmu modeļuzdevumus. EOF Consulting LLC signed contracts BIZIN-I-2019/731 and SKV-L-2019/115 with LIAA for recieving support from ERAF projects ( and

We received a grant from Olaine municipality as part of the Iedvesma competition: www.seb.lv/iedvesma