# Fluid mechanics

Fluid mechanics is the branch of physics concerned with balance and movement of fluids and fluid systems under the influence of external and internal forces. The fundamental difference between the rigid body and the fluid is the mobility of the molecules. Rigid body moves as a set of mass points of a given shape, the fluid does not have its own shape and, contrary to the rigid body under the action of forces irreversibly deforms, its particles are brought into motion, and flow in current bounded by solid walls or interface (level). The goal of fluid mechanics is to explain phenomena and processes occurring in fluids and fluid systems using physical laws and predicting the behavior of fluids and fluid systems in certain conditions, to determine the distribution of fluid properties, i.e. pressure, density, velocity, temperature, concentration, etc. and possibly changes in these variables over time in different locations within the liquid. Research of two- and multi- phase systems flow, including the movement of solid particles in a fluid is the theoretical basis of many engineering disciplines. The study of fluid and fluid systems mechanics at the Institute of Hydrodynamics ASCR , v. v. i., is focused on theoretical and experimental investigation of the flow of suspension, the movement of particles and sediment in close and open conduits, tanks and reservoirs, mixing processes of fluid systems, as well as on mathematical modelling and numerical simulation, calibration and verification of flow models based on the results of experimental research, on experimental methods, and on analysis of a turbulent flow. With the development of new techniques and technologies are increasing the possibility of experimental research on a range of non-invasive methods and methods for understanding the structure of current and local values , especially vector velocity and density. Experimental methods, similarly like numerical methods have developed in a separate area of knowledge and it is necessary to pay them adequate attention. |

Two-phase flow

Experimental methods and measurements in fluid mechanics

Computational Fluid Dynamics

Sediment transport

Fluid flow and processes in agitated vessels and reactors

Bc. Ondřej Gebouský

Ing. Jan Haidl, Ph.D.

Ing. Mikoláš Kesely

Ing. Václav Kolář, CSc.

Ing. Jiří Konfršt, Ph.D.

Ing. Karel Mařík

prof. Dr. Ing. Václav Matoušek

Ing. Michael Mildner

Ing. Jakub Novotný

doc. RNDr. Zdeněk Skalák, CSc.

Ing. Lukáš Svoboda

Bc. Václav Šmíd

prof. Ing. Pavel Vlasák, DrSc.

Bc. Miroslav Vrána

Skalák, Z. (**2021**). An optimal regularity criterion for the Navier–Stokes equations proved by a blow-up argument. *Nonlinear Analysis: Real World Applications*. **58**(April), 103207.

Messa, G. V., Matoušek, V. (**2020**). Analysis and discussion of two fluid modelling of pipe flow of fully suspended slurry. *Powder Technology*. **360**(January), 747-768.

Šulc, R., Ditl, P., Jašíková, D., Kotek, M., Kopecký, V., Kysela, B. (**2020**). The minimum recording time for PIV measurements in a vessel agitated by a high-shear tooth impeller. *Fluid Dynamics*. **55**(2), 231-240.

Matoušek, V., Kesely, M., Chára, Z. (**2019**). Effect of pipe inclination on internal structure of settling slurry flow at and close to deposition limit. *Powder Technology ***343**, 533–541.

Šulc, R., Ditl, P., Jašíková, D., Kotek, M., Kopecký, V., Kysela, B. (**2019**). The effect of Particle Image Velocimetry setting parameters on local velocity measurements in an agitated vessel. *Chemical Engineering & Technology ***4****2**(4), 827–834.

Matoušek, V., Krupička, J., Kesely, M. (**2018**). A layered model for inclined pipe flow of settling slurry. *Powder Technology ***333**, 317–326.

Guo, Z., Caggio, M., Skalák, Z. (**2017**). Regularity criteria for the Navier–Stokes equations based on one component of velocity. *Nonlinear Analysis: Real World Applications ***35**, 379–396.

Chára, Z., Kysela, B., Konfršt, J., Fořt, I. (**2016**). Study of fluid flow in baffled vessels stirred by a Rushton standard impeller. *Applied Mathematics and Computation* **272**(3), 614–628.

Skalák, Z. (**2016**). A regularity criterion for the Navier-Stokes equations based on the gradient of one velocity component. *Journal of Mathematical Analysis and Applications* **437**(1), 474–484.

Vlček, P., Kysela, B., Jirout, T., Fořt, I. (**2016**). Large eddy simulation of a pitched blade impellermixed vessel – Comparison with LDA measurements. *Chemical Engineering Research and Design* **108**, 42–48.

Kolář V., Šístek J. (**2015**). Corotational and compressibility aspects leading to a modification of the vortex-identification *Q*-criterion. *AIAA Journal* **53**, 2406–2410.

Ben-Nun, R., Sheintuch, M., Kysela, B., Konfršt, J., Fořt, I. (**2015**). Semi-analytical characterization of turbulence from radial impellers, with experimental and numerical validation. *AIChE Journal ***61**(4), 1413–1426.

- Ing. Karel Mařík
- Ing. Jakub Novotný
- Bc. Václav Šmíd
- Bc. Miroslav Vrána