Vortex Simulation Research Articles

Steric effect induces enhancement of electroconvective flow near electrochemical interfaces.

Electroconvection, occurring near electrochemical interfaces, propels the movement of ions and water, leading to intricate phenomena rooted in the fine interplay between fluid, voltage, and ion. Here, neglecting ionic interactions, by incorporating the steric term into the Poisson-Nernst-Planck-Stokes coupling equation, direct numerical simulations of electroconvective vortex near nanoslot-bulk interfaces are conducted. For the steric effect, the steric number is introduced to discuss the factors and laws affecting the vortex. We illustrate the substantial enhancement of electroconvective vortex due to the steric effect of ions within the nanoslot. Upon increasing the steric number, the cation concentration in the nanoslot is enhanced, resulting in the expansion of the electric double layer (EDL). The EDLs on the walls inside the nanoslot come into contact with each other, causing the EDLs to overlap, consequently increasing the total charge within the EDLs inside the nanoslot. This EDL overlap enhances the charge density of the extended space charge layer, leading to the enhancement of the electroconvective vortex. Further, our scaling analysis, corroborated by direct numerical simulation and existing data, establishes the scaling of slip velocity, jointly regulated by the steric number and voltage difference. By modulating the membrane transport characteristics, the steric effect reduces flow structure size and flux fluctuations, which offers new perspectives for manipulating ion transport and flow instability.

Lessons Learnt from the Simulations of Aero-Engine Ground Vortex

With the startup of the aero-engine, the ground vortex is formed between the ground and the engine intake. The ground vortex leads to total pressure and swirl distortion, which reduces the performance of the engine. The inhalation of the dust and debris through a ground vortex can erode the fan blade, block the seals and degrade turbine cooling performance. As the diameter of the modern fan blade becomes larger, the clearance between the intake lip and the ground surface is smaller, which enhances the strength of the ground vortex. Though considerable numerical studies have been conducted with the predictions of the ground vortex, it is noted that the accurate simulation of the ground vortex is still a tough task. This paper presents authors’ simulation work of the ground vortex into an intake model with different crosswind speeds. This paper tackles the challenge with a parametric study to provide useful guidelines on how to obtain a good match with the experimental data. The influence of the mesh density, performance of different turbulence models and how the boundary layer thickness affects the prediction results are conducted and analysed. The detailed structure of the flow field with ground vortex is presented, which can shed light on the experimental observations. A number of suggestions are presented that can pave the road to the accurate flow field simulations with strong vorticities.

Interference effect on super large twin cooling towers exposed to stationary tornado-like vortices

A comprehensive investigation was conducted aiming at the interference effects on wind pressure distribution, aerodynamics characteristics, structural stability and reinforcement areas of super large twin cooling towers exposed to tornado-like vortices, and the effects of swirl ratios of tornados, grouped tower layouts, and relative central distances between the towers and the tornado were analysed based on a tornado-like vortex simulator. Two types of rigid model wind tunnel experiments were constructed for base forces and wind pressure distribution measurements. The experimental results demonstrate that the interference effects on base forces and local wind pressures are significantly influenced by the swirl ratios, central distances, and grouped tower layouts, etc. Moreover, the layout with a tornado located on the side of tandem twin cooling towers (along with the tornado translation direction being perpendicular to the central axis of the tandem combined twin cooling towers) is the most unfavourable, resulting in obvious amplification effects on base forces and local wind pressures compared with an isolated tower, and the maximum of interference factors (IFs) is 1.68 and 1.41 for the along-wind total wind force coefficient and minimal net mean pressure coefficient respectively. Subsequently, local stability indices and time-variant dynamic reinforcement envelopes were selected as the other evaluation criteria for estimating the interference effects on the cooling towers exposed to the tornado-like vortices, and the interference effects result in enlargements of the structural responses with the maximal IF of 1.36 for the inside meridional reinforcement. Finally, the various interference criteria at aerodynamic loading and structural reinforcement aspects were contrastive analysed, showing that the criterion of time-variant dynamic reinforcement area envelopes is a more reasonable criterion for evaluating the interference effects on the super large cooling towers exposed to the tornado-like vortices. This investigation aims to contribute to a better understanding of the wind-related effects of the cooling towers exposed to extreme non-synoptic winds, particularly tornadic vortex impacts.

Effect of transient vortex interactions on the size and strength of Jupiter’s Great Red Spot

Jupiter’s Great Red Spot (GRS) is among the largest discrete weather features in the Solar System. Although observed for at least 200 years, the GRS is shrinking, particularly in the past 50 years. Studies of long-lived terrestrial anticyclonic features, known as blocks, demonstrate that they can be sustained, in part, by interactions with transient vortices. Motivated by these results and observations of the GRS absorbing smaller vortices, we conduct three-dimensional simulations of a GRS-like vortex. Control simulations omit forced vortex interactions, while a set of experimental simulations include GRS interactions with transient anticyclones of varying frequency and intensity. Comparison of these simulations allows isolation of the role of such mergers in the GRS evolution. We find that the GRS is larger following periodic vortex interactions relative to control simulations without mergers. Similarly, analysis of upper troposphere eddy potential vorticity and dynamic tropopause potential temperature anomalies suggests the GRS is strengthened by vortex interactions. The degree to which the GRS is sustained increases with interaction frequency and transient anticyclone intensity. These results are consistent with terrestrial blocking dynamics and support the theory that the GRS is modulated by persistent interactions with smaller vortices.

Enhancing Wind Farm Efficiency Through Active Control of the Atmospheric Boundary Layer’s Vertical Entrainment of Momentum

In contemporary wind farm design, the primary focus has traditionally been on reducing wake interference to optimize energy capture from horizontal wind flows. However, with the scaling up of wind farms, their interaction with the Atmospheric Boundary Layer (ABL) evolves, making vertical entrainment the main mechanism for the exchange of momentum and energy. This study introduces a methodical approach to augment the efficiency of large-scale offshore wind farms by actively controlling this vertical entrainment of momentum within the ABL. The strategy involves the precise engineering of advection fluxes to alter wind flow dynamics, utilizing turbines as effective vortex generators, toward a process of ”regenerative wind farming.” This setup aims to create a vorticity and vertical flux system akin to those observed in highly unstable ABLs. Expanding upon previous studies that focused on single Vertical Axis Wind Turbines (VAWTs), our research explores the implementation of multi-rotor systems equipped with lift-generating wings. These systems are designed to exert forces perpendicular to the prevailing wind direction, thus creating trailing vortices and directing the flow orthogonally for improved vertical advection. This research is part of a comprehensive investigative framework that combines experiments and multifidelity simulations. The current study extends those findings to wind farm simulations, aiming to assess the impact of ABL control on a full wind farm scale. The first part of the work validates an established analytical wind farm performance model against real wind farm data for thirty-one wind farms in the North Sea and Baltic Sea. The results confirm the predicted trend of decreased performance with increased wind farm size and density. The model is used to calculate the performance of a wind farm for varying regimes of vertical entrainment due to the creation of large-scale circulatory systems. The results are compared against 3D vortex simulations of the full wind farm in ”regenerative wind farming” mode. Our results demonstrate a notable improvement in wind speeds at the turbine hub height and the potential to double the feasible density of wind farms without compromising efficiency compared to traditional setups. These findings suggest a promising pathway towards a more sustainable and profitable future in wind energy, achieved through the strategic manipulation of ABL momentum, regenerating the energy in the wind farm.

Population viability analysis on the Iranian endangered goat breeds

Iranian goat breeds, including Markhoz, Adani, and Najdi, are considered as endangered populations because of the downward trend of breeding goats and flocks, habitat loss, using other breeds in reproduction, and the presence of survival-threatening factors. This research aims to investigate the current status and provide the necessary information to conserve these three endangered populations. For this purpose, the census data and the required parameters were collected from the available resources and flocks during the years of the project implementation. Then, two scenarios, the past and future dynamics of the population assuming continuing existing conditions, were simulated using the population viability analysis (PVA) method. Finally, the sensitivity analyses of parameters affecting the viability criteria were done. PVA was conducted using the Vortex simulation program version 10.5.6. The past dynamics simulation of the population showed that the biological parameters and assumptions used in the model have valid and reliable values and frequencies, and they can be used in the simulation of different management scenarios. Based on this scenario, the inbreeding rates (∆F) for the Markhoz and Adani populations have reached above the critical level of 0.5%. The future dynamics simulation of the population showed that the process of increasing inbreeding and decreasing genetic diversity would accelerate, and the breeds' extinction probability would start in 2026, 2033, and 2031 for Markhoz, Adani, and Najdi, respectively. The mean time to the first extinction was also 15.4 ± 2.53, 26.68 ± 3.75, and 13.96 ±1.78 years, respectively. The sensitivity analyses indicated that adult does overharvest, the frequency of feed limitation, and competition with other breeds had the highest effect on the population viability criteria of the investigated breeds. Markhoz, Najdi, and Adani goats need urgent conservation measures. The results obtained in this research may prepare a suitable framework for providing conservation programs.

Examination of Vorticity and Divergence on a Rotating Turbulent Convection Model of Jupiter's Polar Vortices

AbstractThe correlation between divergence and vorticity has traditionally served as a signature of convection in rotating fluids. While this correlation has been observed in the JIRAM brightness temperature data for Jupiter's polar vortices, it is notably absent in the JIRAM images. This discrepancy presents a new challenge in determining whether this correlation can serve as a reliable signature of convection in rapidly rotating atmospheres. In this study, we analyzed data from a three‐dimensional simulation of Jupiter's polar vortices using a deep convection model. Our findings confirm the theoretical prediction of a negative correlation between divergence and vorticity in the northern hemisphere. Interestingly, this correlation is weaker within the cyclones compared to outside them. The skewness of upflows and downflows plays an important role in this negative correlation. We also observed that the correlation varies with height, being strongest near the interface and decaying away from it. The correlation diminishes when the resolution is reduced. Furthermore, our findings suggest that the geostrophic approximation may not be suitable for the Jovian atmosphere, particularly in the stable layer. Both tilting and stretching effects contribute to the material derivative of vorticity, with the tilting effect dominating in the unstable layer and the stretching effect prevailing in the stable layer. This suggests a transfer of vorticity from the convectively unstable layer to the stable layer. Consistent with observations, we also noted an upscale energy transfer from smaller to larger scales.

Longitudinal evolution of phase vortices generated by rotationally interleaved multi-spiral

Phase vortices exhibit significant applications and hold promising prospects across various scientific fields. However, while extensive attention has been devoted to the two-dimensional transverse plane of these vortices, their longitudinal properties have received comparatively limited exploration. Our study focuses on the longitudinal evolution of phase vortices, encompassing an investigation of variational topological charges and phase distributions. The investigation employs the rotationally interleaved multi-spiral, characterized by multiple identical spirals arranged in an azimuthally symmetric rotation, to modulate phase distributions by the variable spiral radius versus the azimuthal angle. Initially, we analyze the modulation effect theoretically, delving into propagation properties and vortex formations. Subsequently, through numerical simulations of vortices generated by both single and multi-spiral setups, we examine the longitudinal evolution of topological charges and phase distributions. The analyses reveal a step-wise reductant topological charges and a tortuous increasing spatial variations of phase singularities in transmission direction, with the dependency on both propagation distance and number of multi-spiral. The outcomes hold significant potential applications in optical communications and optical tweezers.

The Okubo–Weiss-type topological criteria in two-dimensional magnetohydrodynamic flows

The Okubo–Weiss (Okubo, Deep-Sea Res., vol. 17, issue 3, 1970, pp. 445–454; Weiss, Physica D, vol. 48, issue 2, 1991, pp. 273–294) criterion has been widely used as a diagnostic tool to divide a two-dimensional (2-D) hydrodynamical flow field into hyperbolic and elliptic regions. This paper considers extension of these ideas to 2-D magnetohydrodynamic (MHD) flows, and presents an Okubo–Weiss-type criterion to parameterize the magnetic field topology in 2-D MHD flows. This ensues via its topological connections with the intrinsic metric properties of the underlying magnetic flux manifold, and is illustrated by recasting the Okubo–Weiss-type criterion via the 2-D MHD stationary generalized Alfvénic state condition to approximate the slow-flow-variation ansatz imposed in its derivation. The Okubo–Weiss-type parameter then turns out to be related to the sign definiteness of the Gaussian curvature of the magnetic flux manifold. A similar formulation becomes possible for 2-D electron MHD flows, by using the generalized magnetic flux framework to incorporate the electron-inertia effects. Numerical simulations of quasi-stationary vortices in 2-D MHD flows in the decaying turbulence regime are then given to demonstrate that the Okubo–Weiss-type criterion is able to separate the MHD flow field into elliptic and hyperbolic field configurations very well.

Insight into blade tip vibration and deformation characteristics of boiler circulation pumps induced by tip leakage vortex under different tip clearances

For circulating pumps in large power plant boilers, tip leakage flow is the main cause of blade fatigue. To investigate the correlation between tip leakage vortex and blade fatigue, in this paper, the bidirectional fluid structure coupling method is used to simulate the full flow field of the boiler circulating pump under different tip clearance sizes. The accuracy of the delayed detached vortex simulation method is verified by combining the external characteristics and vibration characteristics of the pump. It is obtained that tip leakage vortex is the main cause of blade tip vibration and deformation. Under deep stall conditions, the increase in tip clearance size suppresses the vibration displacement of the blade leading edge, while the opposite is true under optimal conditions. After decomposing tip leakage vortex, it is found that the compression–expansion term played a major role in the deformation of the blade tip, while the viscous dissipation term and the stretching term mainly affected the vibration frequency. At optimal working conditions, the main frequency of blade vibration is basically consistent with the main frequency of vortex generation. In deep stall condition, as the tip clearance size increases, the amplitude of the vibration main frequency decreases and the number of harmonic frequencies decreases, while the optimal condition is the opposite.

Non-equilibrium Dynamics of Vortices in Two-Dimensional Quantum Gases: Determining the Dynamical Scaling Region Using the Mahalanobis Distance

When a system undergoes a rapid quench from a disordered to an ordered phase, it does not order instantly but instead relaxes towards equilibrium over time. During this relaxation, the dynamical scaling hypothesis predicts that the length scale of ordered regions increases, with later patterns statistically similar to earlier ones except for a change in global scale. Quantum gases are one of many systems in which such out of equilibrium behaviour is predicted to occur. Here, we present a method for systematically testing when dynamical scaling is taking place, by quantifying the similarity of the rescaled two-point correlation function over time using the Mahalanobis distance. Data on the velocity field of a two-dimensional quantum fluid, generated from point vortex simulations, are used to illustrate the application of this method.

Simulation of vortices and numerical evaluation of heat transfer using multiwalled carbon nanotubes-based hybrid nanofluid for viscous flow sensor

ABSTRACT In this paper, we aim at the simulation of setup for vortex generation and measurement. This project will lead to designing the experimental setup to create vortices and development of heat flow sensors. The working fluid for the vortex generator is hybrid nanofluid such as Iron (III) Oxide-MWCNT and propanol. The usage of these hybrid fluids was considered due to their better physical and chemical properties compared to water and other conventional fluids. Ansys Fluent was used to simulate the experiment. Viscosity of the fluid increases for both hybrid nanofluids, from inlet to outlet by a magnitude of 10 times (for Fe3O4 + MWCNT: 5.3 × 10−5 Pa.s to 6.3 × 10−4 Pa.s; for Al2O3 + MWCNT: 7.5 × 10−5 Pa.s to 6.5 × 10−4 Pa.s), for laminar flow (Reynolds number = 400). Vortex generation increases the viscosity of the hybrid mixture but not water (for water, it stays constant across the channel at 4.9 × 10−4 Pa.s). Vortex induced viscosity is seen in hybrid mixtures. Strain thinning due to vortex formation is not observed, therefore the behavior of the mixtures is along the lines of Newtonian fluids.

Numerical simulation of streamer, pressure wave, and vortex induced by nanosecond pulsed surface dielectric barrier discharges

In this study, a two-dimensional fluid model is employed to simulate the streamer, pressure wave, and vortex in surface dielectric barrier discharge driven by nanosecond pulse voltage (ns-SDBD). It comprises a numerical model with two interconnected modules: discharge dynamics and gas flow dynamics. These modules are coupled through the physical variables including ‘EHD force’, ‘thermal source’, ‘velocity field’, ‘gas temperature’, and ‘gas pressure’. Our research primarily focuses on the underlying physical mechanisms of pressure waves and vortices for plasma-based flow control. The generation of pressure waves is attributed to the rapid gas heating by pulsed discharge, whereas the formation and development of the vortex are related to the ionic wind (EHD effect) provided by the plasma. To thoroughly understand and optimize flow control performance, an investigation into the effects of various discharge parameters, such as voltage amplitude and polarity, is conducted. Additionally, several SDBD modules are arranged in series, each featuring a dual three-electrode configuration. Subsequently, the dynamic behaviors of multiple streamers, pressure waves, and vortices, along with their interactions, are explored.

A330-300 Wake Encounter by ARJ21 Aircraft

Today, aviation has grown significantly in importance. However, the challenge of flight delays has become increasingly severe due to the need for safe separation between aircraft to mitigate wake turbulence effects. The primary emphasis of this investigation resides in elucidating the evolutionary attributes of wake vortices in homogeneous isotropy turbulence. The large eddy simulation (LES) method is used to scrutinize the dynamic evolution of wake vortices engendered by an A333 aircraft in the atmospheric milieu and assess its ramifications on the ARJ21 aircraft. The research endeavor commences by formulating an LES methodology for the evolution of aircraft wake vortices, integrating adaptive grid technology to reduce the necessary grid volume significantly. This approach enables the implementation of axial and non-axial grid adaptive refinement, leading to more accurate simulations of both axial and non-axial vortices. Numerical simulations are conducted using the LES approach to scrutinize three distinct rates of turbulence dissipation amidst the ambient atmospheric turbulence, and the results are juxtaposed with Lidar measurements (Wind3D 6000 LiDAR) of wake vortices acquired at Chengdu Shuangliu International Airport (CTU). Subsequently, the rolling moment of the following aircraft is calculated, and three-dimensional hazard zones are determined for the A333. It is found that during the approach phase, the wake turbulence separation minima for an ARJ21 (CAT-F) following an A333 (CAT-B) is 3.35 NM, which represents a reduction of approximately 33% compared to ICAO RECAT (Wake Turbulence Re-categorization). The findings validate the dependability of the fine-grained mesh used in the vortex core region, engendered through the adaptive grid method, which proficiently captures the Crow instability and the interconnected phenomena of vortices in the numerical examination of aircraft wake. The safety of wake encounters primarily depends on the magnitude of environmental turbulence and the development of structural instability in wake vortices.

Assessment of implicit adaptive mesh‐free CFD modelling

SummaryThis work presents details and assesses implicit and adaptive mesh‐free CFD modelling approaches, to alleviate laborious mesh generation in modern CFD processes. A weighted‐least‐squares‐based, mesh‐free, discretisation scheme was first derived for the compressible RANS equations, and the implicit dual‐time stepping was adopted for improved stability and convergence. A novel weight balancing concept was introduced to improve the mesh‐free modelling on highly irregular point clouds. Automatic point cloud generations based on strand and level‐set points were also discussed. A novel, polar selection approach, was also introduced to establish high‐quality point collocations. The spatial accuracy and convergence properties were validated using 2D and 3D benchmark cases. The impact of irregular point clouds and various point collocation search methods were evaluated in detail. The proposed weight balancing and the polar selection approaches were found capable of improving the mesh‐free modelling on highly irregular point clouds. The mesh‐free flexibility was then exploited for adaptive modelling. Various adaptation strategies were assessed using simulations of an isentropic vortex, combining different point refinement mechanisms and collocation search methods. The mesh‐free modelling was then successfully applied to transonic aerofoil simulations with automated point generation. A weighted pressure gradient metric prioritising high gradient regions with large point sizes was introduced to drive the adaptation. The mesh‐free adaptation was found to effectively improve the shock resolution. The results highlight the potential of mesh‐free methods in alleviating the meshing bottleneck in modern CFD.

Persistent gravitational radiation from glitching pulsars – II. Updated scaling with vortex number

ABSTRACT Superfluid vortices pinned to nuclear lattice sites or magnetic flux tubes in a neutron star evolve abruptly through a sequence of metastable spatial configurations, punctuated by unpinning avalanches associated with rotational glitches, as the stellar crust spins down electromagnetically. The metastable configurations are approximately but not exactly axisymmetric, causing the emission of persistent, quasimonochromatic, current quadrupole gravitational radiation. The characteristic gravitational wave strain h0 as a function of the spin frequency f and distance D from the Earth is bounded above by $h_0 = 1.2\substack{+1.3 \\ -0.9} \times 10^{-32} (f/30\,\,{\rm Hz})^{2.5} (D/1\,\,{\rm kpc})^{-1}$, corresponding to a Poissonian spatial configuration (equal probability per unit area, i.e. zero inter-vortex repulsion), and bounded below by $h_0 = 1.8\substack{+2.0 \\ -1.5} \times 10^{-50} (f/30\,\,{\rm Hz})^{1.5} (D/1\,\,{\rm kpc})^{-1}$, corresponding to a regular array (periodic separation, i.e. maximum inter-vortex repulsion). N-body point vortex simulations predict an intermediate scaling, $h_0 = 7.3\substack{+7.9 \\ -5.4} \times 10^{-42} (f/30\,\,{\rm Hz})^{1.9} (D/1\,\,{\rm kpc})^{-1}$, which reflects a balance between the randomizing but spatially correlated action of superfluid vortex avalanches and the regularizing action of inter-vortex repulsion. The scaling is calibrated by conducting simulations with Nv ≤ 5 × 103 vortices and extrapolated to the astrophysical regime Nv ∼ 1017(f/30 Hz). The scaling is provisional, pending future computational advances to raise Nv and include three-dimensional effects such as vortex tension and turbulence.

Effect of Horizontal Resolution on a Meso‐β‐Scale Vortex Simulation in an Extreme Rainstorm on 22 May 2020 Over South China: A Contrastive Study Based on Different‐Resolution Ensembles

AbstractA transient extreme rainstorm that occurred over Guangzhou city, China, on 22 May 2020, has been investigated based on two ensemble prediction systems (EPSs), one with 9‐km (TRAMS9km‐EPS) and the other with 3‐km (TRAMS3km‐EPS) grid spacings, respectively. The results show that the better performance in the rainstorm event of TRAMS3km‐EPS than that of TRAMS9km‐EPS has been attributed to the reasonable simulation of an eastward propagating meso‐β‐scale convective vortex (MβCV). The composite evolution of the good‐performing members for the two EPSs has verified the important role of the MβCV in modulating the structure of low‐level jet (LLJ) to converge toward the Guangzhou city, facilitating the formation of the rainstorm. In comparison to the gravity wave disturbance when LLJ passed through the mountains in TRAMS3km‐EPS, the topographic effect induced the moist air to ascend deeply in TRAMS9km‐EPS, which directly led to earlier outbreaks of convection and rainstorm processes and affected the structural intensity of the upstream MβCV. Quantitative PV diagnosis has demonstrated that the dispersedly strong high‐PV systems in TRAMS3km‐EPS were caused by positive feedback effect between meso‐scale convective systems and diabatic heating, and were favorable for the entire cyclonic development of MβCV. The unsymmetrical PV tendency around the moving MβCV under the combined effect of diabatic heating and advection process in TRAMS9km‐EPS resulted in a rapid propagation of this system. However, the symmetrically developed PV system within the MβCV in TRAMS3km‐EPS allowed the enhanced cyclonic circulation to persistently affect Guangzhou city, inducing extreme rainstorms similar to the observations.

High-Order DG Schemes with Subcell Limiting Strategies for Simulations of Shocks, Vortices and Sound Waves in Materials Science Problems

High-Order DG Schemes with Subcell Limiting Strategies for Simulations of Shocks, Vortices and Sound Waves in Materials Science Problems

Simulation and Experimental Study of Near Wall Flow Vortex on Multiple Rows of Holes

Simulation and Experimental Study of Near Wall Flow Vortex on Multiple Rows of Holes

The possible impact of escaped captive American mink (Neogale vison) on the population of feral mink in Denmark.

The Danish feral mink (Neogale vison) population can be divided into wild-born and captive-born mink newly escaped from a farm. The impact of the captive-born mink on the population of feral population is unknown. Captive-born mink has lately been estimated to make up 25-30% of the feral mink population. In December 2020 Danish mink farms were decommissioned until January 2023. The aim of this study was to: 1) Examine whether a supplementation of farmed mink into the feral mink population influence the population growth and extinction rate of the feral mink, 2) Investigate which parameters affect the viability in feral mink populations the most. The age and mortality of 351 mink and the reproduction of 85 adult females culled by hunters from 2019-2022 were determined in three distinct geographic areas of Denmark (Jutland, Zealand, and Bornholm). VORTEX simulations were used to model the population viability and to simulate the impact of a supplementation of captive-born mink into the wild population. Simulations show that changes by 30% in the parameters: fecundity, percentages of breeding females and mortality influenced population size influenced the final population size significantly. The initial population size and inbreeding did not affect the population growth significantly. The simulations showed that the mink population in the regions of Jutland and Zealand could go extinct within 15 to 30 years without any supplementation of captive-born mink to the feral population. The population on Bornholm will however remain stable with current levels of mortality and reproduction even without supplementation of captive mink.