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Turbulence and Turbulent Flow Modeling 5: Mechanism of turbulent flow (2)

Yumiko Katsumura

5.1 Turbulent flow and vortex tube The previous column explained that velocity difference causes turbulent flow and that eddies are formed in the turbulent flow. When eddies are visualized, they look like tubes; therefore, the visualized eddies are c...
- Apr 9, 2026
Turbulence and Turbulent Flow Modeling 4: Mechanism of turbulent flow (1)

Yumiko Katsumura

In the previous columns, we have seen the image of turbulent flows, their merits and demerits, and the relationship between turbulent flows and weather forecast. How does a turbulent flow occur? This column will introduce the mechanism of turbulent f...
- Apr 2, 2026
Turbulence and Turbulent Flow Modeling 3: Relationship between turbulent flow and the weather forecast

Yumiko Katsumura

3.1 Weather calculation and fluid simulation Fluid simulation is used to forecast the weather that is seen on TV and in the newspaper every day. While weather observation data is important for the weather forecast, fluid simulation also plays a large...
- Mar 19, 2026
Turbulence and Turbulent Flow Modeling 2: What is a turbulent flow? (2) - Advantages and disadvantages of a turbulent flow

Yumiko Katsumura

2.1 Is a turbulent flow a nuisance? Turbulent flow is all around us. It can be beneficial in some cases and not in others. When the airflow around a vehicle becomes turbulent, air resistance increases. Automobile companies, therefore, try to suppress...
- Mar 12, 2026
Turbulence and Turbulent Flow Modeling 1: What is turbulent flow? (1) - Actually something very familiar!

Yumiko Katsumura

1.1 Introduction What comes to mind when you hear the term “turbulent flow”? Engineers working in fluid simulation are familiar with the term. Even so, many of these engineers only care about setting the turbulent flow boundary conditions...
- Mar 5, 2026
Mastering Multiphase Flow with Fluid Simulation: 22. Liquid-liquid two-phase flow analysis with two-fluid model

Yumiko Katsumura

Liquid-liquid two-phase flow analysis with two-fluid model Two-fluid model is an example of gas-liquid two-phase flow analyses or liquid-liquid two-phase flow analyses. It is also called distributed multi-phase flow model, Euler-Euler model, Euler mu...
- Jan 15, 2026
Mastering Multiphase Flow with Fluid Simulation: 21. Boiling flow analysis (free surface flow analysis with phase change)

Yumiko Katsumura

Boiling flow analysis (free surface flow analysis with phase change) Boiling flow analysis is an example of gas-liquid two-phase flow analyses. By using recent computers that have evolved dramatically, issues concerning multi-phase flows have come to...
- Jan 8, 2026
Mastering Multiphase Flow with Fluid Simulation: 20. Cavitation flow analysis

Yumiko Katsumura

Cavitation flow analysis Cavitation flow analysis is an example of gas-liquid two-phase flow analyses. Cavitation is a phenomenon in which steam cavities are generated and disappear in an area in which the pressure of a liquid flowing at a high speed...
- Dec 25, 2025
Mastering Multiphase Flow with Fluid Simulation: 19. Solidification/melting analysis III

Yumiko Katsumura

Solidification/melting analysis III This section continues to explain solidification/melting analysis. Until the previous section, the analysis target was a flow in which the liquid phase and the solid phase of the same substance were contained, like...
- Dec 18, 2025
Mastering Multiphase Flow with Fluid Simulation: 18. Solidification/melting analysis II

Yumiko Katsumura

Solidification/melting analysis II This section continues to explain solidification/melting analysis. The flow of the liquid phase in solid-liquid coexistent state is affected by the volume fraction of the solid phase (solid phase rate). In other wor...
- Dec 11, 2025
Mastering Multiphase Flow with Fluid Simulation: 17. Solidification/melting analysis I

Yumiko Katsumura

Solidification/melting analysis I Solidification/melting analysis is an example of liquid-solid two-phase flow analyses. For a micro approach of solidification phenomena, modeling of processes of solidification core generation and crystal growth is r...
- Dec 4, 2025
Mastering Multiphase Flow with Fluid Simulation: 16. Dew condensation analysis III

Yumiko Katsumura

Dew condensation analysis III This section continues the introduction of dew condensation (evaporation) analysis. The Particle Tracking Method described in this column is combined with the dew condensation analysis. As shown in Figure 1, a water drop...
- Nov 27, 2025
Mastering Multiphase Flow with Fluid Simulation: 15. Dew condensation analysis II

Yumiko Katsumura

Dew condensation analysis II This article introduces another example of dew condensation/evaporation analysis. When you want to analyze dew condensation and evaporation on a wall surface of a solid such as a window inside the house or a defroster, th...
- Nov 20, 2025
Mastering Multiphase Flow with Fluid Simulation: 14. Dew condensation analysis I

Yumiko Katsumura

Dew condensation analysis I Dew condensation and evaporation can be analyzed as a type of gas-liquid two-phase flow analyses. The analysis targets are dew condensation on windows and walls inside a house and defrosters—a function to defog windo...
- Nov 13, 2025
Mastering Multiphase Flow with Fluid Simulation: 13. Analysis example – Chocolate fountain

Yumiko Katsumura

Analysis example – Chocolate fountain The transient start-up of a chocolate fountain is analyzed to demonstrate the VOF (Volume of Fluid) method. Have you ever seen a chocolate fountain? Sometimes they can be seen at parties. Melted chocolate f...
- Nov 6, 2025
Mastering Multiphase Flow with Fluid Simulation: 12. Particle tracking analysis VI

Yumiko Katsumura

Particle tracking analysis VI This article uses an analysis example to illustrate how to apply external forces to particles using the particle tracking method. Fluid simulation analysis software must often be able to apply external forces, other...
- Oct 30, 2025
Mastering Multiphase Flow with Fluid Simulation: 11. Particle tracking analysis V

Yumiko Katsumura

Particle tracking analysis V This section describes the liquefaction of particles analyzed by using the particle tracking method. Two primary methods are used to analyze the liquefaction of particles. One is converting a particle into a liquid film a...
- Oct 23, 2025
Mastering Multiphase Flow with Fluid Simulation: 10. Particle tracking analysis IV

Yumiko Katsumura

Particle tracking analysis IV This section discusses generation of chemical species during evaporation and volatilization of particles using the particle tracking method.Evaporation and volatilization must be modeled for reactant particles. For the s...
- Oct 16, 2025
Mastering Multiphase Flow with Fluid Simulation: 9. Particle tracking analysis III

Yumiko Katsumura

Particle tracking analysis III This section explains particle evaporation and volatilization of using the Particle Tracking Method.In the 1990s, excess CO2 emission was a major environmental issue. Improving the combustion efficiency of industri...
- Oct 9, 2025
Mastering Multiphase Flow with Fluid Simulation: 8. Particle tracking analysis II

Yumiko Katsumura

Particle tracking analysis II This section describes condition settings for the particle tracking method. The particle tracking method is one method used for particle simulation analyses.An accurate multi-phase analysis for sand or dust particles, wh...
- Oct 2, 2025
Mastering Multiphase Flow with Fluid Simulation: 7. Particle tracking analysis I

Yumiko Katsumura

Particle tracking analysis I The particle tracking method is useful for multi-phase flow analyses. The behavior of particles can be used to visualize gas-liquid two-phase flows, gas-solid two-phase flows, liquid-solid two-phase flows, and gas-liquid-...
- Sep 25, 2025
Mastering Multiphase Flow with Fluid Simulation: 6. Free surface flow analysis V

Yumiko Katsumura

Free surface flow analysis V This section looks at an example of a micro-scale free surface flow.Modern electronic devices such as smartphones. Electronic components smaller than 1 mm in size are densely mounted on a circuit board. Mass production of...
- Sep 18, 2025
Mastering Multiphase Flow with Fluid Simulation: 5. Free surface flow analysis IV

Yumiko Katsumura

Free surface flow analysis IV This chapter discusses calculation time, which is an important consideration when free surface problems are solved using the VOF method.Since free surface flow analyses using the VOF method are transient analyses, they r...
- Sep 11, 2025
Mastering Multiphase Flow with Fluid Simulation: 4. Free surface flow analysis III

Yumiko Katsumura

Free surface flow analysis III This chapter continues the discussion about the VOF method and contains additional analysis examples. In the VOF method, the volume fraction of a fluid occupying each element of the computational domain is defined by th...
- Sep 4, 2025
Mastering Multiphase Flow with Fluid Simulation: 3. Free surface flow analysis II -VOF (volume of fluid) method-

Yumiko Katsumura

VOF (volume of fluid) method This section describes VOF method, which is a commonly used free surface flow analysis method. In the VOF method, a volume fraction of a fluid occupying each element in the computational domain is defined by F where (0 &l...
- Aug 28, 2025